"We Fixed a Truck" is the thirty-ninth episode in the fifth season of Adventure Time. It is the one hundred and forty-third episode overall.
The episode opens with Finn pushing an old truck, that he found in a tree on a hill, while singing a song about his luck in finding the truck. He honks the truck's horn to wake Jake up. A sleepy Jake appears at the window with BMO. Jake, surprised at the truck, stretches to the ground with BMO and asks Finn where he found it. Finn says he found it in the woods and named it "Hot Daniel." He says they could do some "pretty neat stuff" with it. Jake wants to try the truck, but Finn states it is broken. After discovering that BMO and Ice King know nothing about cars, Jake thinks of Banana Man.
Banana Man comes to the Tree Fort, bringing some soda and a radio. He checks the engine and sees the problem: the cylinder head is missing. Finn and Jake do not understand, so Banana Man explains. He finds the missing parts in the back of the truck, but states that there's a reason why the past owners removed it. He then sings a song while the four fix the truck during a montage.
Sunset comes, and Jake asks if they want to continue fixing in the morning. They all agree, except for BMO, who replaces its batteries and continues working while listening to Starchy's late-night show on the radio. A Banana Guard calls Starchy and says he thinks Princess Bubblegum has been replaced by a lizard. Banana Man returns, saying he could not sleep and says he figured out why the past owners removed the engine block. He claims "it was really nice hangin' with you fellas," and puts emphasis on how alone he is. BMO is surprised Banana Man doesn't have a girlfriend. Banana Man replies by saying he does not want to be alone but is good at ignoring it by doing projects around his home.
Morning arrives, and Finn shows up, giving BMO a cup of coffee. Finn compliments them on their good work. As Finn approaches Banana Man, the latter suddenly wakes up and screams, "I fixed it! Are we best friends yet?!" Banana man tells Finn that he got a new cylinder head from the junkyard, and they proceed to mount it on the truck. They continue their work on the truck, even making their own biodiesel from oil, and finally complete it. Afterwards, the group sit in the car, as Banana Man takes a deep breath and inserts the ignition key. To their delight, the truck activates, and they speed off towards the Candy Kingdom.
Banana Man sees a female Banana Guard, and the three encourage Banana Man to go talk to her. He refuses, so Jake forces him to drive nearer to the guard. The group then starts complimenting Banana Man, supposedly making him more appealing. The guard does not seem to be interested, but they are oblivious to this and continue praising Banana Man. They then drive away, covering the guard with dirt and dust, enraging her in the process. They drive into the Kingdom and see Princess Bubblegum running away from an angry mob. Jake grabs her, places her in the truck and gives her a cup of tea. BMO, who still believes Bubblegum is a lizard, offers her a bug. The imposter eats the bug with her long tongue and transforms into a giant reptile. Before it can do any harm to them, Jake pushes it off the truck. The lizard starts attacking the Kingdom.
Banana Man turns the truck around and accelerates at Finn's orders. While they are driving, Finn pulls Banana Man's peel off and throws it under one of the tires, causing the truck to rotate at high speed. The vehicle then goes up a ramp, but before the truck slams into the lizard, Jake turns into a parachute to steer the gang safely onto the ground. The lizard, along with the truck, explodes in a large fireball. A dirty Princess Bubblegum comes out of the sewer and narrowly dodges a flaming Hot Daniel. She sees Finn and Jake and warns them about reptilian replicants taking over the kingdom, but sees that they already have it under control. The female Banana Guard appears, and states that Banana Man is coming with her. Banana Man, still naked, is completely surprised and asks, "What? Really?" The guard replies by having Banana Man arrested for "public indecency." BMO cries because 'Hot Daniel' is dead, while Finn and Jake give thumbs up.
- Reptilian Clone
- Princess Bubblegum
- Ice King
- Candy People
- Ice King still inhabits the Tree Fort.
- The Promotional Artwork reveals that Banana Man had been waiting for Finn and Jake to call him.
- The title card shows that the truck was stuck on a tree.
- Background artist Santino Lascano's wedding date (8/18/2012) reappears in this episode, this time on the truck's mileage counter.
- This is the first time a female Banana Guard has been shown.
- The engine described by Banana Man is a petrol engine with spark plugs, however, they go on to make biodiesel fuel which doesn't work on engines which use spark plugs.
- The female banana guard's spear has a set of rings at both ends as opposed to the regular spears with only rings at the bottom.
- Multiple background music from previous episodes return, including from "When Wedding Bells Thaw" and "Belly of the Beast."
- In one scene, Finn, Jake, BMO, and Banana Man go to the same spa in the Breakfast Kingdom first shown in "Hitman" to steal some grease in order to make biodiesel.
- Banana Man makes a reappearance and mentions many events from his debut episode "The New Frontier."
- Finn names the truck "Hot Daniel," an exclamation he uses in "Vault of Bones" when Flame Princess saves him from the Giant Goo Skull.
- During the car-fixing montage, BMO does the same dance on the hood of the car that Banana Man was practicing in "The New Frontier."
- The episode's "lizard replicant" sub-plot references the "reptoid hypothesis" conspiracy theory advocated by David Icke and others, which claims that many—if not all—people in power are actually shape-shifting reptilian aliens.
- Starchy's late-night radio show Graveyard Shift is a reference to Coast to Coast AM, a talk and call-in show which frequently deals with paranormal and conspiracy topics, notably including David Icke's "reptoid hypothesis." Though the show is only broadcast for 4 hours, in most markets it is followed by an additional hour of clips from a previous show—matching the 5 hour run time Starchy's show claims.
- The idea of a "lizard replicant" may also refer to Visitors from the V science-fiction franchise. They are reptilian humanoids that disguise themselves as normal humans in order to aid their invasion of Earth.
- The pick-up truck which Finn, Jake, and Banana Man fixed is a 1954 Chevrolet 3100 with several fictionalized additions/modifications such as a different grille, dashboard panel, and push-button ignition.
- While BMO is sleeping, their screen displays a pair of flying toasters. This is a reference to a screensaver module included in the After Dark computer software series.
- When BMO searches their memory for information on fixing cars, their screen displays a waving flashlight. This is a reference to the waving flashlight icon displayed when searching for files in Windows 98.
- Cinnamon Bun is seen in the angry mob chasing the fake Princess Bubblegum despite refusing to return to the Candy Kingdom in "Earth & Water."
- BMO crushed a soda can on their head and threw it away, but it was not seen on the ground right afterwards.
- When night comes and Banana Man starts to walk away to go back to his house, he is not wearing his black shoes. He is shown wearing shoes in every other scene in the episode.
- BMO's star is sometimes on their head or on the side of their controls while singing the song "Hanging Out Forever."
- Jake exclaims "Biodiesel!" after mixing the fuel, however the description that Banana Man gives is for a gasoline engine, which does not function with biodiesel.