The Mushroom War (also referred to as the Great Mushroom War) was an apocalyptic event that occurred roughly a thousand years before Adventure Time. The war crippled and eventually resulted in the near-annihilation of the human species and left their civilization in ruins throughout the Land of Ooo.
Not much is known about The Mushroom War or the events leading up to it, except that it ended with a mushroom bomb being dropped on what was once America, awakening The Lich and ending most of life on Earth. The episodes "Finn the Human" and "Jake the Dog" support this, as Finn wishes the Lich, a product of the mushroom bomb, never existed. This implies that either some country used the essence of the Green Catalyst Comet to make the weapon, or it was a regular nuke that released the evil essence upon explosion. When the wish is granted, Finn is transported to a world where the sorcerer Simon Petrikov has sacrificed himself to stop the mushroom bomb and freezes the entire Earth in the process. Despite some destruction, without the detonation of the mushroom bomb, humanity continues to exist. Also, in "Finn the Human," Farmworld Marceline suggests that the mushroom bomb likely concluded the war as she states that the world would have been annihilated if Simon had not stopped the bomb with his ice powers.
The war likely ended approximately one thousand years before the events of Adventure Time. Marceline's flashback in "Simon & Marcy" is explicitly stated in a time card in the episode to have taken place 996 years ago prior to the present setting. The exact year(s) that the war took place have never been stated, though it can be concluded that the Mushroom Bomb was dropped sometime after, at the earliest, 1985, as in "Everything Stays", Two Bread Tom, a surviving human, is depicted singing the theme song to the sitcom Mr. Belvedere, which premiered that year; in "Simon & Marcy" the Ice King is depicted singing the theme song and making reference to the sitcom Cheers, which premiered in 1982, further supporting the 1980s timeframe of the war. However, due to the appearance of a Generation 3 iMac computer in the episode The Lich, (which started becoming available to mass public consumption in 1998), it can be assumed that the war occurred sometime after the year 1998. This would also help explain why Internet-derived expressions and phrases are frequently used by characters. Modern smartphones are seen in Patience St. Pim's flashback of the human era, in "Elemental"; this could indicate that the Great Mushroom War began sometime around 2010. Further evidence that proves that the War took place in the 2000's is in the episode "Sons of Mars," where Abraham Lincoln briefly shows a penny that has a date with the first two numbers being "2" and "0" (the rest of the numbers are obscured).
The end of the war left much of the world devastated and devoid of much life. The infrastructure that had existed throughout the land had been mostly destroyed. The little human infrastructure that survived, such as girder bridges and office buildings, now lay in ruin. Evidence of the war appear in the form of abandoned military vehicles, ruined army blockades, bombed buildings and crashed warplanes. A great deal of human technology also remained scattered throughout the land. Abandoned and destroyed vehicles were a common sight in the devastated landscape and their rusting skeletal remains can be seen in the backgrounds of several episodes.
Despite the great destruction, some humans managed to survive the war, such as Simon Petrikov (Ice King), Moe, the tribe of humans led by Two Bread Tom, Elise, and the family lines that eventually led to humans in the current setting of the series, including Finn and Susan Strong; Marceline, a half-human/half-demon, also remained as one of the war's only survivors. Nonetheless, most presumably perished during the war. In the flashbacks from "Obsidian," Marceline's mother Elise is shown to be dying from an unknown illness which is strongly implied to be radiation poisoning from the nuclear fallout: this suggests this was the fate of most humans who survived the war. Throughout the episode they try to find a fallout shelter called the "Clubhouse," with Marceline ultimately arriving to find the vault door open and the skeletal remains of its inhabitants, implying the shelter failed to protect them from the Mushroom War. In "I Remember You," Simon says to Marceline that they may be alone after the apocalypse, and "Simon & Marcy" depicts a post-war society devoid of any other humans.
Some individuals survived the war through special or supernatural means. Simon Petrikov was kept alive by the magic of his crown, as he states in his note to Marceline in "I Remember You". Hunson Abadeer, Marceline's dad, was seen with Marceline in a flashback in "Memory of a Memory" in the remains of a ruined diner, though considering that he is nowhere to be seen in Marceline's flashbacks in "I Remember You" and "Simon & Marcy" it is likely that he may have been in the Nightosphere during the war and its immediate aftermath. Therefore, it can be inferred that they were separated sometime after the Mushroom War.
In "Everything Stays", it is stated that some years following the initial aftermath of the war, a major climate change developed, implied to have been a result of the war and the dropping of the bomb. Having detected abnormal atmospheric readings, Two Bread Tom's tribe of humans sailed away from their makeshift forest settlement in a renovated freighter in search of a safer place to thrive.
Despite the destruction from the war, the land slowly began to recover and soon life was once again allowed to freely inhabit the earth. Only a few signs of the nuclear devastation remained in Ooo. One example was in the episode "The Vault," where Shoko helps Princess Bubblegum establish her new kingdom by covering up an irradiated river at the site of the Candy Castle. In the process of covering it up, Shoko becomes disfigured and mutated by the effects of the waste and appears as she had in premonitions in earlier episodes of the series. The episode implies that the Candy Kingdom is built atop a pond of nuclear waste.
Along with the rise of new civilizations, such as the Candy Kingdom, a diverse variety of intelligent life settled down in Ooo. Many were able to recover or develop technology for their own use. Examples of this are universal translator devices and holographic newspapers. It is unknown whether these are based on prewar technology (the year of the war was never stated, but we know that it must have happened sometime in or after the 2010s because modern smartphones can be seen in Patience St. Pim's flashback of the human era, in "Elemental". Despite this, most human inventions, especially those related to transportation, remained lost to the inhabitants of Ooo. In "The New Frontier," Jake mentions this when he says that "rocket ships haven't been reinvented yet," implying that the technology to build conventional space-faring vessels was lost during the Mushroom War.
The first mention of the war in continuity was in "Video Makers," when Finn and Jake discover government copyright warnings before the movies they watch for their film club. Even though the civilizations that created these warnings would have been long gone by their time, they decide to abide by them to avoid breaking the law.
Evidence or clues of former civilization
- To see a chronological list of episodes, see List of episodes.
In many (but not all) episodes of Adventure Time, there are hints or clues regarding the world and the civilization that existed prior to the Mushroom War, including as follows:
- In the opening shot three nukes, arrows, axes, and swords are seen. The swords, arrows, and axes imply the stagnation of technological development, in reference to an Albert Einstein quote: "I know not with what weapons World War III will be fought, but World War IV will be fought with sticks and stones." A pair of headphones, Princess Bubblegum's amulet, a severed arm (possibly belonging to Shoko) and an axe can be seen in the trees, and two casette tapes are on the ground. A broken television from the 21st century is in front, implying that this was possibly some sort of bomb shelter that was destroyed. An object resembling a VHS tape is near the TV, alongside a creature's skull.
- An asphalt/concrete road can be seen above Marceline's cave, along with a driveshaft and two axles to the right.
- "Tree Trunks": Traffic signs, which have since somehow mutated into Sign Zombies. The painting in Tree Trunks' house appears to be of Egyptian pyramids.
- "The Enchiridion!": When Finn and Jake first walk through the forest of Mount Cragdor, pieces of metal and some dryers/washers can be seen as they look for the sacred book. Some of the pieces at the top, right corner of the path may be sinks.
- "Business Time": Ancient artifacts frozen in icebergs, including computers, a bike, baby shoes and the Business Men. When the Businessmen try to remember where they came from, they seem to be in pain. Finn also uses a flamethrower built from two fuel tanks connected to a rifle by a tube. A tank is also seen later in the episode.
- "My Two Favorite People": When Finn and Lady Rainicorn confront Jake and Tiffany, the bottoms of upturned cars can be seen in the ground. Jake also uses a military issue phone and headset, and some mutated and regular skulls can be seen near the fire pit where Jake, Lady Rainicorn, and Finn are sitting. The bottom of Lake Szelezon is covered by a horde of gold, and the area closest to the shore has the remains of a ship wreck on it.
- "The Witch's Garden": The remains of a highway system and a plane's wing can be seen near Gary's nest; The River of Junk is essentially a river of mundane pre-war garbage. A car door can also be spotted near the River of Junk. When Gary picks up Finn a computer monitor can be seen with a tree growing in it. An airplane wing can been seen nearby Gary's nest. The Video recorder that the witch uses is probably from before the war.
- "Ocean of Fear": Underwater city ruins and vehicles appear, and a brief scene shows a damaged aircraft carrier and a stranded tank. An even briefer scene depicts two dead bodies on a couch in the remains of a pre-war living room. Finn and Jake also take to the depths in a submarine which contains a fire extinguisher, which is most likely from before the war. One can see the remaining tops of cars while they are floating over what might have been an ancient road. There are also ruins of old prewar buildings and battleships that can be seen when Jake tries to teach Finn to swim. A prewar tank can be seen stranded on the building as well. The buoy that Finn stands and the wrench he uses to knock himself out are most likely from before the war.
- "City of Thieves": When Finn and Jake are in Penny's tent, a double barrel shotgun can be seen sitting among a pile of gold coins, and a tommy gun can also be seen in the background. In addition, the chest stolen from the tower contains what appears to be a hand-held video game system in the bottom left corner. Also, right before the wizard vanishes a can opener can be seen on the tower next to him. The fishing rod used to take Penny's basket and the boots that Jake stole are probably also from before the war. When Finn falls into the King of Thieves' room a keyboard can be seen in the background.
- "What is Life?": Neptr is made from an old microwave, a tin can, small tank treads, a circuit board and insulated wires.
- "Henchman": At the start of the episode, Finn and Jake are playing on the remains of what looks like a dragon. In the foreground, an old wooden boat is buried in the soil, and in the background, the remnants of a castle can be seen.
- "His Hero": In Billy's cave, TVs, a bathtub, and other items can be seen lying around.
- "It Came from the Nightosphere": The final battle between Hunson Abadeer and Marceline and Finn takes place on what appears to be an ancient battle field, covered in the ruins of an old castle, and scattered with the bones of dead soldiers. Finn uses one of these dead soldier's swords to fight Abadeer.
- "The Eyes": Jake plays Moonlight Sonata on his viola, which was written by Beethoven. Jake himself mentions that it is written by Beethoven (mispronouncing it "Beet-hoven"), and also mentions Mozart ("Mot-zart").
- "Loyalty to the King": When Finn and Jake are walking through the forest there are destroyed walls and swords in the background.
- "Storytelling": There are remains of radios and debris scattered throughout a forest. The young bear is also spraying graffiti on what looks like an overgrown van.
- "Power Animal": Three broken TVs is seen beside the trunk of Finn and Jake's tree house when Jake walks up to the water girls.
- "The Other Tarts": Various boats and whale skeletons can be seen in the Desert of Doom.
- "To Cut a Woman's Hair": A wrecked car can be seen in the background of the forest.
- "The Silent King": The storyboard for "The Silent King" contains the first time The Mushroom War is mentioned by name in the series, heard when Gummy is reading from the rule book. However, this line was cut from the actual episode. The overturned auto mobile that appears during the goblin riot is another artifact from past civilizations.
- "The Real You": A shot of Earth appears, and a huge chunk of it is missing. The missing piece of Earth could have been a result of the Great Mushroom War, or a Catalyst Comet that struck after the war.
- "Death in Bloom": Debris of civilization, including numerous police vehicles, in the Land of the Dead and crashed UFOs. They also take an escalator down to the entrance to the Underworld, and a TV is in the ground when they "sneak" past the entrance.
- "Susan Strong": The Hyooman tribe live in the ruins of either an underground city, or a bunker that failed at its purpose. In the underground city, a car, a refrigerator, and some sort of submarines/huge ships can be noticed. In the storyboard, a warning reading "Biohazard Danger" appears on the hatch, although this was cut from the episode. Which can be proof that The Hyooman Tribe was once humans and they were turned to mutants by the radiation from the Mushroom War. Also, in one brief scene, the camera pans over a pile of junk. Upon closer inspection, one can see what appears to be a robot arm sticking out of the debris. There is what seems to be the front of a tank sticking out of the garbage when Finn and Jake first jump down the hatch.
- "Mystery Train": The train itself is most likely a relic from pre-war times. Parts of the locomotive, its passenger cars, and cars interior have a style like those of trains of the 1800s. Just as Finn and Jake are boarding the train, a railroad "X" crossing sign and the remnants of a former second track can be noticed.
- "Go With Me": The Drive-in theater houses the remains of many aged cars.
- "Belly of the Beast": A wrecked wall and a sword were seen in the forest and the remains of a damaged car rest in the throat of the monster as Finn and Jake return to confront the bears in the stomach.
- "Video Makers": Video cassettes feature movies such as Heat Signature that were made prior to the war. Jake even mentions the Mushroom War in the episode. The fact that Finn and Jake say they see the FBI warning on all the movies they "dig up" is further evidence they are of pre-war origin.
- "Heat Signature": The title card shows Finn and Jake standing on a tearing, fading billboard which stands in a destroyed urban background. In front of Marceline's cave there is a defunct highway that acts like an awning. There are also the remains of an old car across from the cave entrance. Later, the ghosts take Finn and Jake to the top of what looks like a torn up skyscraper with a helicopter crashed on the roof. The skyscraper does have a helicopter pad on top, and other tall buildings can be seen nearby.
- "Mortal Folly": The title card is reminiscent of a mushroom cloud. The base of the Lich's power is a ruined subway station with deserted trains and littered with human skeletons scattered on the floor as if they had been killed that very moment around the station. Character designer Andy Ristaino has stated that these skeletons "were supposed to feel like they were east coast commuters ... all bundled up for winter." Outside the station is what appears to be a nuclear missile. There are also ruins of buildings in the background. the subway and its platforms are like those in New York or New Jersey.
- "Mortal Recoil": When Finn is telling Jake what he was giving Possessed Princess Bubblegum he says Plutonium, which was used to make Nuclear bombs.
- "Morituri Te Salutamus": The destroyed arena is most likely The Colosseum in Italy from before the Great Mushroom War.
- "Memory of a Memory": Many of Marceline's childhood memories appear to be around the ruined remains of civilization. She is seen as a little girl living in a ruined city with a derelict tank near houses, then later catches her father eating her fries at a destroyed diner. In Marceline's memory of a little girl, the unknown city in the background can be seen on fire. Around Ash's house, there are many tires and other debris strewn about the area. There is also what appears to be a mobile home on the roof of his house, which has an aged tow truck balanced on top.
- "Hitman": Outside the Breakfast Kingdom is a desert with an abandoned railroad car and an abandoned dump truck with haystack near it.
- "The Monster": When Finn and Jake go into the forest some wreckage is seen and during the flashback a wolves' cave is shown to be a broken wall with debris next to it.
- "Wizard Battle": The arena for the battle seems to be a broken down sport stadium. Also, when the sun sets, city buildings and towers from modern times in the overgrowth of the forest can be seen in the background.
- "The Creeps": A portrait of what appears to be of a city's silhouette. Another painting of a woman with the date 8/18/12.
- "Beautopia": Beautopia appears to be the ruins of an underground shopping mall or luxury resort due to signs left on the sides of buildings such as "Eat," "Sale," "Buy" and "Food." Also, the Lub Glubs live inside pool floaties.
- "Thank You": Outside the home of the Snow Golem appears to be a snow covered bulldozer. The house in which the Snow Golem lives could also be a remnant from before the war, as suggested by Tom Herpich's promo art for the episode, which depicts a family of humans (or humanoids) living in the house in a time before it was covered with snow.
- "The New Frontier": When Finn and Jake see a rocket built or found by Banana Man, Jake states that rockets haven't been re-invented yet when Finn is worried he might die. There is also a limousine buried in the ground near the home of the Banana Man along with some missile and fighter jet parts.
- "Holly Jolly Secrets Part I": When Finn first stumbled upon the Ice King collecting his tapes, there appears to be a ruined backhoe in the distance. The location that the Ice King buried his suitcase full of tapes looks like an old junkyard. Next to Finn is a boat with a harpoon on the front of it. A truck, a car, and a small plane also lie near the Ice King and Finn. When Finn and Jake are digging for the suitcase, a shoe is hanging from a tree branch and a TV is seen underground where the suit case was buried. In this hole is also a skeleton with a green hat. A trumpet is also seen tied to a tree branch above the Ice King. The video camera Ice King used to record his diary most likely dated before the war as well.
- "Holly Jolly Secrets Part II": The last tapes played showed the Ice King as a human (Simon Petrikov). The Ice King's crown apparently turned him into what he is now, as seen in the videos. An undamaged city is seen outside the window that Simon is talking in front of. Simon said he purchased the magic crown from a dock worker in Northern Scandinavia, a region of Europe. It is also possible to see a map of the eastern part of the Americas behind Simon in the first part of the video.
- "Marceline's Closet": Near the beginning of the episode, Finn sings a nursery rhyme about the war when playing hide & go seek. The lyrics are "Over the mountain, the ominous cloud, coming to cover the land in a shroud. Hide in a bush, a basement a cave, but when cloud comes a-huntin' no one's a-safe."
- "Paper Pete": At the end of the episode when Finn and Jake are walking away from the library, one can see buildings rising from the ground surrounding the library. The library itself seems to be made before the Mushroom War, too, because the Library appears to be the top of a building that is stuck in the ground.
- "Ghost Princess": When Ghost Princess arrives there are some broken walls in the bushes. The Cemetery looks like it was made before the Mushroom War, and has a lot of modern-day objects in it. Multiple cars and a passenger train car can be noticed in the cemetery. Some broken highways and wind turbines can be seen during Ghost Princess's flashback. The Squeez-E-Mart appears like a convenience store of the former civilization formerly run on wind turbines and solar panels that have since become derelict. At the end a wind turbine engine can be seen by Finn and Jake's campfire.
- "Dad's Dungeon": There is a lot of modern day wreckage within the Finn and Jake's attic.
- "Five Short Graybles": In the study of the Story Teller "A.K.A Cuber" is a holographic "globe" of Earth (similar to the globe of Earth usually used in study images), with a massive gash over a corner of the world just like Earth's depiction in "The Real You." It also seems that Finn's catapult for his "super high five" is partially made of some sort of military device.
- "Web Weirdos": The piece of wall that Jake and Finn bounce off of when doing stunts seems to have rebar. When Ed goes to find Barb a present in the forest, he passes a derelict vehicle in the background and by the dead knight, one can see an electronic panel on some of the damaged wall to the left. There is also more damaged wall and a car seen when Finn and Jake try to escape.
- "Daddy's Little Monster": There are tourist plaques hanging from Hunson Abadeer's kitchen cabinets. The plates are for Vegas, Orlando, and Arizona.
- "In Your Footsteps": Ruined buildings can be seen rising out of the forest Finn and Jake were walking around at night and when the bear is riding his bicycle.
- "Hug Wolf": At the beginning of the episode, there are some ruins near the Tree of Blight.
- "Princess Monster Wife": A picture of a city in winter can be seen in the Ice King's room.
- "Card Wars": The card game Card Wars uses technology that seems to be from before the Mushroom War.
- "Sons of Mars": At the beginning of the episode, an abandoned double-tracked railroad line is shown. On the left track, an out-of-service rail car is seen. Later, Magic Man's derelict house is surrounded by many vehicles, which are to be abandoned. The house is also full of skulls. Also, Earth is shown from space showing the hole on its side. Abraham Lincoln offers Death a penny in exchange for Jake's soul. The penny's production date is "20XX D" (minted in Denver); it also says "IN XXD WE TRUST" ('X' meaning the letter or number was covered up by moss). It can be presumed this says “IN GOD WE TRUST”, the motto on every US Coin.
- "Burning Low": When Princess Bubblegum is trying to explain why Finn cannot be with Flame Princess, on her hologram a picture of the earth can be seen that looks similar to the one on "Five Short Graybles." During Jake's dream about being promoted to president, the remains of a highway and a plane wing can be seen; however, since this was in a dream, this might not be canonical.
- "King Worm": Finn and Jake crawl through a tunnel after shrinking down to fit into a mousehole. Beneath the tunnel are a number of broken and abandoned subway cars.
- "Lady & Peebles": During one of her Korean conversations, Lady Rainicorn mentions Vietnamese noodles, which refer to the former existence of the nation of Vietnam. Princess Bubblegum also uses GPS, a system developed by the US government in the 1970s.
- "Who Would Win": There are broken ship hulls and other ship parts strewn around the lake.
- "Ignition Point": While searching the Flame King's castle, Jake and Finn can hear the conspirator reciting lines from Hamlet. Jake at least seems somewhat aware of Shakespere's work, as he comes up with a plan to find the conspirator using the same scheme in Hamlet, then declares that it was his original idea needlessly.
- "The Hard Easy": A wrecked vehicle can be seen when Finn and Jake are building a fire and a refrigerator is seen by the entrance of the cave where Finn and Jake hide.
- "I Remember You": The Ice King is seen to have a lot of modern day junk and items in his "Past Room" including a US Highway 101 sign as well as an image of a comet hurtling for Earth. During the song "Remember You," clips are shown: what appears to be a destroyed city, and a street corner where Marceline is crying, when Simon Petrikov comes and takes a teddy bear, Hambo, from a destroyed toy store and gives it to her. Earlier in the episode, Marceline shows the Ice King a newspaper clipping of when he was still Simon Petrikov. The US 101 sign from the Ice King's Past Room is seen again in the destroyed city, which can reason that Marceline and Simon's meeting occurred on the Pacific Coast of the United States along the 101 corridor between Washington and California.
- "The Lich": For a brief second, one can see the planet Earth when Jake makes the Enchiridion map of the multiverse enhance. The blown up chunk of the planet is visible. Earth is depicted as the second planet from the sun, because, for reasons as yet unknown, the sun expanded and consumed Mercury.
- "Finn the Human": Scenes from the Mushroom War are shown, such as Simon Petrikov on a hill staring at war planes, a destroyed city with the Lich and other mutant creatures walking against a green mushroom cloud, and Simon freezing a nuclear bomb-like weapon before it detonates.
- "Five More Short Graybles": Finn and Jake discover an old book of nursery rhymes, which they believe to be a spellbook. The Story Teller also mentions at the end of the episode that "nobody has had five fingers for 20 blabillion glaybles."
- "Up a Tree": When Finn and the Squirrel are flying off on a Frisbee, there is a shot of a destroyed highway in the background. Finn and Jake are also playing a modified version of dog fetch.
- "All the Little People": The hill Finn and Jake are sitting on at the beginning of the episode appears to in fact be a collapsed building that is covered with grass and ivy. Also, the area surrounding the hill seems to be the ruins of a human city, as at least one other ruined skyscraper can be seen as well as the ruins of a highway system. This landscape was seen in the world of the mini-people at the end of the episode, with the same ruined buildings and highway.
- "Jake the Dad": When Mr. Fox shows the Baby Eating Fox and the Babies book to the other foxes, some of the foxes are resting on what appears to be an old abandoned car. The book itself could also be of pre-war origin.
- "Mystery Dungeon": In the second room they enter, it looks like a pre-war kitchen with destroyed tile floors and an oven.
- "All Your Fault": In Princess Bubblegum's lab, there is a mobile of the solar system, and the giant hole in the earth can be seen.
- "Bad Little Boy": Marshall Lee and flies past some broken ships and There are two broken items behind the stage.
- "Vault of Bones": While Flame Princess and Finn walk through the woods to find a dungeon, there is the remains of an old car buried in the undergrowth in the background.
- "The Great Bird Man": Various boats and whale skeletons can be seen in the Desert of Doom. This location was previously visited in the episode "The Other Tarts."
- "Simon & Marcy": The majority of this episode takes place 996 years ago, a few years after the war, in a mostly destroyed city. There appear to be mutated creatures that ooze slime out of pores from their bodies, and a pink, sentient bubblegum-like substance taking over parts of the city. Also, when Simon and Marceline walk to the Clambulance, they seem to have been walking on a dry river, greatly resembling a part of the Los Angeles River. Abandoned tanks can also be seen with a red star on them in the background indicating those tanks are from the Soviet Union. This means that Russia may have invaded the West Coast.
- "BMO Lost": Throughout the episode, the background of the forest is filled with ruins, such as cars, chairs, and bottles. When BMO first lands, Bubble emerges from an old cup. Bubble's accidental Rube Goldberg machine ends with a tree falling on the skeleton of a long-dead hunter. BMO and Bubble discuss Ricky's departure by what appears to be an old pipe system.
- "Princess Potluck": When Ice King goes to the forest, there appears to be the remaining top of a red car sticking out of the ground as well as a square pitcher.
- "James Baxter the Horse": Finn and Jake keep a lot of modern day wreckage around the house and in their bathroom. When cheering people up, Finn and Jake come across a sad ghost on a potentially abandoned railroad.
- "The Suitor": In the Vapor Swamps, one can see a few decomposed buildings in the background.
- "The Party's Over, Isla de Señorita": When the Ice King first hears Island Lady's singing, ruined buildings can be seen in the water off the coast of the island, similar to the ruins seen in "Ocean of Fear."
- "One Last Job": A broken tape recorder can be seen in the tree house walls.
- "Another Five More Short Graybles": The DVD's that the Ice King has seem to be from before the Mushroom War due to the fact that they have human actors. The house that Mr. Fox lives in might be from before the war, as indicated by how old and easily the walls were broken down. Also, the engine Finn and Jake use for their time machine looks like it was manufactured before the war.
- "Candy Streets": Around the train tracks near the Candy Train Station, there are remnants from what appears to be a previous rail system, as well as the wreckage of other train cars.
- "Be More": The MO Co. was built over 1,000 years before the show takes place, before the war. Moe was also a human from before the war, although his body parts were replaced with robot parts, making him only part-human.
- "Frost & Fire": During the scene where the Ice King's snowball crushes a tree, a muffler from a car can be seen buried in the ground next to Finn.
- "The Vault": When Shoko is riding up to the mansion, various wrecked buildings can be seen littering the country side. Also, while the Candy Kingdom is under construction, the candy people are cleaning up a river of toxic waste.
- "Love Games": The entrance to the Slime Kingdom, which is located near the Bad Lands, is littered with sunken ships, crashed airplanes, bones, and what appears to be a mid-20th-century space capsule.
- "Red Starved": The entire episode takes place in an underground city either made of sand or transformed into sand. Some old structures can be seen. Marceline taps a soldier made of sand with a spoon, causing him to fall apart. Finn estimates the ruins to be over 500 years old, so its possible that the ruins date to after the Mushroom War.
- "We Fixed a Truck": The episode focuses on a truck that Finn found in a forest. The truck, nicknamed "Hot Daniel" is later fixed by Finn, Jake, BMO and Banana Man. It appaers to be a 1954 Chevrolet 3100, thus making it pre-war.
- "The Pit": Joshua, and later Finn and Lady Rainicorn, explore a decrepit dungeon. However, the time frame for when the dungeon was created is not known, and it is possible that the ruins date to after the war.
- "James": While Finn, Jake, Princess Bubblegum, and James traverse through the Desert of Wonder, various ruined buildings and highway systems can be seen in the background. There are also some tanks, a missile stuck on the ground, and what appears to be the wing of a military plane with a propeller. The Oozers from "Simon & Marcy" appear to have survived in the desert and play a major role in the episode, where they attack the four characters.
- "Apple Wedding": Lumpy Space Princess emerges from the remains of an old well. In the background is what appears to be an abandoned house.
- "Blade of Grass": The opening shot shows ruined buildings and the remains of what looks like either a bridge or a road system. When Finn is running towards the Forest to get rid of his cursed sword, the remains of what appear to be a plane turbine are seen sticking out of the ground.
- "Rattleballs": The episode takes place in a junkyard, in which the scattered remains of pre-Mushroom War materials seem to be located, such as sofas, wrecked cars, plane parts, and nuclear weapons.
- "The Red Throne": as Flame Princess and Cinnamon Bun are fleeing the Fire Kingdom through the forest, a wrecked car, a wrecked moving trailer, some axes, and a broken speaker can be seen.
- "Betty": Simon creates a portal that jumps back to the time immediately before the Mushroom War to say goodbye to Betty. During Marceline's monologue, the episode flashback to scenes immediately following the war, showing wreckage of a city. When Marceline, Finn, and Jake rush to the Ice Kingdom, they pass by what appears to be an old snow plough.
- "Billy's Bucket List": While attempting to overcome his fear of the ocean, Finn climbs onto an overgrown and abandoned dock. Also, when Finn is swimming beneath the ocean, the remnants of buildings can be seen in the background, similar to what appeared in "Ocean of Fear." However, since the ruins appear in a dream, their authenticty is in question. The background for the scene taking place while Finn and Canyon ride a motorcycle features bombs, a buried car and a lighter, but a large portion of the background is obscured by the camera angle; artist Derek Hunter claims these are a reference to the film Tremors.
- "James II": During the opening shot, there are rusty, old buckets near the dock next to the waterfall.
- "Breezy": While Finn is singing for the first time, he walks past the ruins of a smashed boat and a TV. Lizard Kingdom seems to be the remains of some sort of residential building (judging by the mailbox out front) or an airport (again, judging by the control tower-esque part of the building). There are also ruins and refuse in and around the remains of Lumpy Space Princess' camp.
- "Ocarina": In Jake's fantasy he mentions they old days which shows modern day buildings.
- "Joshua and Margaret Investigations": The house that Joshua and Margaret live in appears to be in the middle of a derelict and bombed-out metropolis. This city is actually most likely San Francisco, since in a background shot of the city in the distance, a red suspension bridge greatly resembling the Golden Gate Bridge can be seen behind the skyscrapers. In the forest near Tree Trunks's house, an abandoned backhoe and the remains of a bank (the "Pantheon of Savings") can be found which is full of old baby toys from modern times.
- "Jake the Brick": As Finn journeys to meet Jake, he walks over what appears to be an old metal pipe before greeting Jake near an old abandoned house. The structure probably dates from before the Mushroom War, due to its deteriorated status.
- "Dentist": When Finn is being lowered down the well, the remains of a building can be seen behind him.
- "The Visitor": Within Finn's Dream is the ruined city from under the ocean.
- "Dark Purple": While Finn, Jake, BMO, and Marceline wait for the Super Porp shipment, they hang around Squeeze-E-Mart, which looks as if it was a pre-war structure. There are some wrecked wind turbines around Squeeze-E-Mart. The ruins of Beautopia reappear. Wrecked Buildings can be seen half sunken in the water when Susan and her friends fly on the drones along with the Super Porp factory. In the vicinity, an underground, seemingly pre-Mushroom War soda factory is still active. Marceline mentions having drunk Super Porp frequently as a child, leading Finn to wonder how Super Porp can still be in production long after the Mushroom War.
- "The Diary": A wrecked car and shopping cart can be see at love tree point.
- "Walnuts & Rain": Seven says Mississippi in his flashback.
- "Jermaine": A piece of debris can be seen by the Tree House when Finn and Jake head of to meet their brother.
- "You Forgot Your Floaties": Magic Man's derelict house, which is surrounded by many abandoned vehicles, is once again visited. Although the house has been retrofitted by Magic Man, its design suggests it is of pre-Mushroom War origin.
- "Be Sweet": The area in and around Lumpy Space Princess’s camp is littered with bombs and swords.
- "Orgalorg": Gunter has a recollection of living throughout history, which includes many events from before the Mushroom War (such as Ancient Egypt, Greece, Rome, and Prohibition, to name a few).
- "Hot Diggity Doom": In Princess Bubblegum's bunker, the remains of a space shuttle and a helicopter can be seen.
- "Bonnie and Neddy": In Princess Bubblegum's flashback, the Mother Gum from which Bubblegum and Neddy spawn out of is stuck to the ceiling of a collapsed, derelict building. When Neddy hides in the cave a two old broken cars and pipe can be seen.
- "Mama Said": Scattered debris can be seen in the forest as Finn and Jake are walking and when they are with Canyon. An abandoned highway bridge is seen in the mushroom fields.
- "Marceline The Vampire Queen": When Finn and Jake chase the vampire essence creature two broken wind turbine posts can be seen.
- "Everything Stays": The near-entirety of this episode consists of flashbacks to events from Marceline's childhood and early adolescence. In a memory which takes place prior to the Mushroom War, young Marceline and her mother are seen living normally in a trailer home. The succeeding flashbacks all take place in the aftermath of the war. In a destroyed city, Simon records a VHS message for Marceline before parting ways with her. Teenage Marceline is seen in another ruined city hunting The Fool, who hides in a blood donation van; she later encounters a tribe of humans in a forest, where stone ruins are seen. The humans later renovate an old freighter to sail away from the territory, and their leader Two Bread Tom talks to Marceline about an impending major change in the atmosphere.
- "Vamps About": The remains of a crashed aircraft, several subway cars, and a rocket launch tower (seen in the corner of a background piece) are seen in the forest. In a flashback, Marceline and the Vampire King fight on the humans' renovated freighter.
- "The Empress Eyes": A flashback shows teenage Marceline's hobo camp, which is located in the remains of a sewage facility littered with industrial tubing and abandoned vehicles.
- "May I Come In?": When Finn, Jake, Marceline, and Princess Bubblegum are in the forest looking for The Moon there are some arrows in trees and in the ground by some tomb stones. There is also what appears to be the remains of an old house when Bubblegum tracks the vampires. Within the forest some modern day debris, weapons, and skulls can be seen.
- "Take Her Back": While in the forest their can be two old wooden shacks in the background. When Finn and Jake are looking for the Moon an old stop sign is seen stuck to a tree The boat house the Moon sleeps in looks pre-Mushroom War.
- "The Dark Cloud": A brief flashback shows Marceline in her childhood trailer home. A chair, a life preserver and some googles can be seen in a bush by the now mortal Vampire King.
- "The More You Moe, The Moe You Know (Part II)": The sole answer to AMO's Hangman video game is "Burgess Meredith", who was an American actor active in the 20th century. One of Moe's memories shows him in the MO Factory having just finished constructing BMO. Through a window, a Fire Giant can be seen being constructed outside. On Moe's desk their are blueprints for a fire giant and the Martian city.
- "Summer Showers": Lumpy Space Princess says that her play takes place in England.
- "Angel Face": The remains of what appears to be the torch from the Statue of Liberty is briefly seen in the desert. There are many bones and old boats in the desert. When Jake and BMO road off some jet plane parts and an old car can be seen.
- "President Porpoise is Missing!": Remnants of buildings, machinery, and transport vehicles are seen by the dock. There is also an old lifeguard post on the beach. The Fish Parliament holds their meetings in the sunken ruins of a shopping mall food court. The mall appears to be part of an entire sunken city, as buildings, cars, and street lights are also seen underwater.
- "King's Ransom": When Jake goes to get the tin can there is some wreckage in the forest. Some on the wreckage is a car, a tank, and some missiles. The cave where Betty hides appears to be an old mine with broken walls, metal poles and a crane.
- "Scamps": Two of the Marshmallow Kids are playing with a globe that has a chunk missing.
- "Flute Spell": When Jake hears Finn's flute music there is some wreckage from behind a tree. There is an old broken game console in Huntress Wizard's house. During Finn's dream two wrecked walls can be seen. When Fin and Huntress Wizard chase the Boar there are some old train cars in the background. After Finn gets one of the boar's tusks there are two more wrecked walls behind Huntress Wizard.
- "Broke His Crown": Within Ice King's crown are the virtual consciousness' of the previous wearers which includes a adolescent boy named Sveinn and an elderly man who is the world's first Santa.
- "Don't Look": One of the signs on Death Mountain is a One-Way traffic sign. There is also some modern day junk within the Hermit's yurt.
- "Beyond the Grotto": Within the pond are some broken TVs, a broken pipe line, shopping carts, a fire hydrant, and license plates.
- "Lady Rainicorn of the Crystal Dimension": During Lady's flashback when she arrives in Ooo. Her barn was old wrecked an abandoned suggesting that is was pre-Mushroom War.
- "I Am a Sword": When Finn and Jake are looking for the Finn sword there is a spatula, a shopping cart, a weight, some weapons, a mannequin, a hat, and some gold coins on the ground. A yellow arrow sign can be sign by the Spikey Village.
- "Normal Man": Normal Man is talking to Tiny Manticore on the same cliff by the wrecked buildings in water from "All the Little People." During the flashback the bus that Magic Man used to run over the Martians is the same bus seen by his house.
- "Elemental": Patience St. Pim calls Ice King Bernini.
- "Five Short Tables": The tree Lumpy Space Prince hides in is filled with household items like books and a mug.
- "Daddy-Daughter Card Wars": The Card Wars tournament is on what appears to be an old oil rig in the middle of the ocean. Charlie lives in an Egyptian pyramid. The pyramid is shown to still be in relatively good condition, suggesting Egypt may not have been targeted during The Great Mushroom War, or that this pyramid was not located near any strategic targets.
- "Preboot": Finn, Jake, and Susan find an old arcade in Beautopia.
- "Reboot": Susan pulls out a large anchor from the ocean.
- "Do No Harm": When Jake throws away the meatloaf a small TV can be seen in the garbage can. Lots of Weapons can be seen in the Grassy Wizard's grass maze. A sword can be seen in a trash can when Finn Fixes Ice King's back.
- "Wheels": Bronwyn and her friends skate at an old skate ramp in the middle of the forest. When Jake skates away from Kim Kil Whan a no parking is briefly seen. Jake and Bronwyn have a thrash off at an old abandoned amusement park.
- "High Strangeness": Princess Bubblegum's remote is shape like Texas. When Bubblegum and Tree Trunks are brought back to Ooo by the aliens a broken storm drain pipe can be seen next to them.
- "Horse and Ball": Jake and BMO visit the junk yard which is filled with a ton of modern day junk and vehicles. During James Baxter's flashback a old tire ca be seen by the river, the horse city James Baxter used to live in is based on a modern day city, and the cave James Baxter find is filled with old modern junk which includes books and toys.
- "The Invitation": The beach has old umbrella and towels on it and Bubblegum and Marceline are sitting on a huge bone buried in the sand.
- "Whipple the Happy Dragon": When Finn, Jake, BMO, and Susan enter the fog there are lots of wrecked ships.
- In "Hide and Seek," a flashback shows Dr. Gross showing her students "the Founder's Song." The song sing about and a video along with it shows after the mushroom war the surviving humans (who were very likely the ones seen in "Everything Stays") left the mainland and moved to the islands and repopulated for generations. A MO Co. blimp can be seen in the Founders' video which indicates that Moe himself used to live on the islands in the past.
- In "Min and Marty," a statue of Two Bread Tom is shown.
- In "Skyhooks," A Skull and Bone made of candy can be seen when Finn and Jake return to Ooo.
- In "Slime Central," A ship can be seen inside a slime bubble when Finn and Jake arrive in the Slime Kingdom.
- In "Happy Warrior," as Ice King is blowing everyone to the Fire Kingdom, the skeletons of winged creatures can be seen in the clouds. A warrior skeleton, bones and weapons can be seen under the Fire Kingdom.
- In "Skyhooks II," Betty Grof suggests using the Enchiridion to create a portal to go back in time a possibly stop the Mushroom War. When Lumpy Space Princess fixes Ooo there are bones seen in the trees. Some debris can be see when Finn looks for Jake. Including fence posts, a wheelbarrow, a skull, and a buried house.
- In "Abstract," When Jake goes to visit Jermaine there is a plane in trees and a mailbox in the bushes. There is a monster skeleton and car parts in the desert where Jake meets James.
- In "Ketchup," Marceline finds an old USB drive which contains picture from before the Mushroom War including one with a young Marceline and her mom.
- In "Fionna and Cake and Fionna," During Other Fionna's flashback there are a lot of broken computer monitors, a keyboard, and an extension cord. Her cave home is also covered in broken monitors and a mini fridge.
- In "Whispers," There are skeletons and an old cable car line where Finn and Fern are fishing. When Finn and Fern and holding onto Sweet P who is running a truck, license plate, wheel, and stop sign can be seen. A bottle can be seen by Sweet P's head. In the swamp there is a slow traffic sign, a wheel, and a burred warrior. Finn chases the Lich's hand to his well of power which is by another subway entrance where there is a missile and broken walls and post. Finn also travels deep down the Lich's lair revealing more subway cars and pipes.
- In "Three Buckets," When Finn and Fern arrive at the field there is a lot of household items on the hills of the field. Finn and Fern walk through a field, where giant nuke bombs are seen. A sword can be seen in the temple.
- In "Always BMO Closing," A traffic cone, motorcycle, an axe, a broken fighter plane, and a missile can be seen when BMO and Ice King are chasing the chipmunk. There are some metal parts by Gumbald's temple.
- In "Son of Rap Bear," When Finn and Flame Princess go to see Rap Bear, a broken wall, an old telephone wire poll, a pot, and a buried bicycle can be seen in the background. Finn and Flame Princess walk by an old playground where a skull and some bones are seen buried next to them. A lot of wreckage can be seen by the Son of Rap Bear billboard during Flame Princess' rap montage. In the Treehouse is a picture of an old damaged building. The rap battle between Flame Princess and Son of Rap Bear takes place in the Wizard Battle arena where old and wrecked buildings can be seen in the background.
- Most of "Bonnibel Bubblegum," is a flashback to 800 years prior to the series. In this time Ooo is a wasteland with very little life. A young Princess Bubblegum scavenged through the land and reached a gas station with many old items from before the war. There is even a poster with a mushroom cloud and the words "never forget", obviously referring to the Mushroom War. There is also a crashed military stealth bomber greatly resembling an F-117 Nighthawk.
- In "Ring of Fire," during Tree Trunk's flashback as a CEO Wyatt mentions that the flowers are from Robot Body Moe, which must mean Moe.
- In "Marcy & Hunson," A small skull and a rope tied to a tree can be seen when Peppermint Butler summons Hunson Abadeer. Bones, rings, and a dead knight with a sword in it's chest can be seen when Finn and Jake take Hunson to see Marceline. Hunson has a flashback a Hunson and a young Marceline from the aftermath of the Mushroom War. The defunct highway in front of Marceline's cave from "Heat Signiture" can also be seen when Finn and Jake take Hunson to Marceline.
- In "The First Investigation," Joshua and Margaret Investigations headquarters reappears but in a state of decay on the same modern town from "Joshua and Margaret Investigations." One of the time slips shows a human woman from the past. An old bicycle can be seen in the attic.
- In "Blenanas," There is an old tire swing and well close by the tree Finn sits by. Finn and Ice King visit the headquarters of Ble magazine. The headquarters is inside a building in the ruins of a city with most the buildings submerged underwater. On the windows of a nearby office building, signs with letters on them can be seen spelling out the words "HELLO BLE?", indicating that more recently after the war, there were survivors in the building who attempted to make contact with anyone inside the Ble headquarters. Inside the headquarters are the skeletons of presumably the writers of Ble, together with the remnants of modern 21st-Century-looking technology such as computers with flatscreen LCD screens and printing equipment. Somehow, the building's fire alarm still works as well.
- In "Temple of Mars," When Finn and Jermaine arrives at Magi Man's house Jermaine claims he hasn't seen a boat in years and there was an old chair in Magic Man's house. Betty's flashback takes place in modern times before the Mushroom War. Within the flashback, she is seen using a cellphone that resembles a Motorola DynaTAC.
- In "Come Along With Me" Marceline tries to convince Princess Bubblegum to call of the Gum War. She reminds her that she lived through the Mushroom War and that she would hate for a similar out come to occur. A flashback briefly occurs showing child Marceline standing in front of a destroying burning city. A flashback shows Simon and Betty talking about GOLB in the modern times before the Mushroom War. A skull and a fossilized skeleton can be seen on the battlefield.
- In "BMO," CGO explains to BMO that Hugo and his inner circle came from Earth to escape a war (unnamed but clearly referring to the Mushroom War) and shows footage of the explosion that created the massive crater on Earth, together with two large nuclear detonations in different parts of the planet. Interestingly, the explosion responsible for the crater seems to have been caused by a large electromagnetic energy bomb of sorts.
- Marceline's flashbacks in "Obsidian" document her and her mother Elise's attempts to locate a fallout shelter sometime after the war, revealing Elise survived for a period of time in the aftermath. Elise is shown to be deathly ill, heavily implied to be radiation poisoning from the nuclear fallout. Eventually, she sends Marceline away to find the shelter herself, as she does not want her to watch her mother die. When Marceline arrives at the shelter, however, she finds the blast door open and the skeletal remains of its inhabitants. Additionally, a pre-war RV appears at the end of the episode which resembles a modified 1977 RAF 2203 "Latviya" Minibus.
- Legends of Ooo: A game on cartoonnetwork.com, mentions the Mushroom War. If one clicks on the radio in Marceline's house, Jake states that, "They stopped making these before the great Mushroom War." In the Forest where the Teenage Bear is found, one can see a car that says "Wash me."
- Adventure Time Battle Party: At the "waiting for opponents!" screen, there are two skeletons, bones and some swords inside the ribcages of the skeletons on the grassy patch. In the arena, the player can find a broken truck and a damaged television.
In "Memory of a Memory" Marceline appears as a young girl in a post-apocalyptic environment. A burning city in the background suggests the Mushroom War had affected that area fairly recently, although plant overgrowth suggests that some time has passed since humans inhabited the area. Marceline is one thousand and three years old, suggesting that the Mushroom War occurred roughly one thousand years into the show's past. This theory was proven when, in "Finn the Human," Farmworld Marceline says that Simon Petrikov saved the world from the Bomb of Death (mushroom bomb) 1,000 years ago to Farmworld Finn.
In "Holly Jolly Secrets Part I" and Part II BMO plays tapes which show Ice King as a young human. The Ice King, then known as Simon Petrikov, narrates a video diary about his life. The early part of his video diary shows him living in what appears to be human civilization, either before or during the war.
A scene in "I Remember You" ends up revealing a memory of Simon traveling through the destroyed world and meeting an alone and crying Marceline. Simon calms her by giving her a toy. During the episode, it had been revealed that they might be the only survivors to the Mushroom War. However, this is unlikely due to the fact that Finn appears to be a normal human boy, meaning some humans may have survived the Mushroom War, though it is not known whether any besides Finn and Finn's dad, Martin are still alive. It later revealed in "Everything Stays" that there were indeed human survivors of the war.
The alternate universe of "Farmworld," created by Finn in an attempt to stop the Lich from existing, further seems to reveal the possible birth of modern Ooo. Although the Mushroom War still occurred, a massive nuclear-like weapon was fired by one of the sides. Though the weapon did not hit initially due to the sacrifice of Simon Petrikov, it ultimately did finally hit the Earth a thousand years later. When it hit, a massive green energy similar to that of The Lich emerged and covered the entire world quickly. It can be assumed that when this "bomb" hit Earth in the actual universe, this began the emerging of the Lich, the Human Apocalypse, and the end of the Mushroom War; leading to the beginning of the transformation of the entire world into what would emerge, over the next thousand years, as Ooo; a world where technology would exist side by side with magic.
|The following information is from the Adventure Time comic book series. It may not be part of the same canon or continuity as the animated series.|
In Issue 4, a still unchanged Marceline can be seen hiding in a cave as mushroom bombs bombard the planet around her, creating the giant gash on the side of the planet. In the collected edition of the comic book, Marceline's coloring in the flashback is changed to the more demon-like look seen in "I Remember You."
In Issue 13, Randall N. Byron states that the first Mushroom War happened 1,002 years ago. However, this is probably false because that would place the episode "Simon & Marcy" (when Marceline is seven years old) six years after the war even though Marceline is already three or four years old before the war in "Everything Stays".
In issue two, after Finn and Jake kill the Lich in outer space, Finn sees Earth and wonders if the hole from the Mushroom War had been there all along.
- In an interview with Pop Candy, Pendleton Ward said that the post-apocalyptic aspect of Ooo was not in the original concept of the series, but emerged as a result of the episode "Business Time," when the writers decided the Business Men being frozen in ice made the world post-apocalyptic, and "we just ran with it."
- It is possible that goo monsters could be former humans mutated by the Mushroom Bomb, theorized by the abundance of the creatures in former highly populated areas, such as the metropolis in the episode "Simon & Marcy." Also, they seem to leak a very similar green goo as the irradiated pools of waste in the same episode aforementioned, as well as the episode "The Vault," it draining out of most of their orifices, such as their ears, eye sockets and mouth. They are seen again in the episode "James," wherein James is turned into one.
- The Mushroom War shares some similarities to the Fallout series' Great war, especially the near extinction of the human species and the large amounts of nuclear weapons launched during the war causing mamy mutations in the survivors.
- It is implied that the Mushroom War was extremely devastating, since when viewed from space, the Earth's continents have deformed and became nearly unrecognizable while a giant crater covers the area where Europe once rested.
- In the episode "BMO", two mushroom bomb explosions can be seen on opposite ends of the planet. This implies that there was more than 1 mushroom bomb.
In other media
- In the YouTube animated show Bravest Warriors (created by Pendleton Ward), a quick frame shows Earth, with a chunk missing from it, seen when Chris is imagining the future.