A Glitch is a Glitch

Synopsis
Ice King creates a computer virus to delete everything except him and Princess Bubblegum. So Finn & Jake try to remove the Virus before it can glitch out the universe.

Plot
The episode starts out with Finn and Jake drawing a picture of Ice King on their computer. Jake tells Finn to "make him look angrier", but by doing so, Jake says it is no longer funny then exclaims that he ruined it. Finn claims that "he has no patience for this animation junk", but then oddly punches himself in the face. Soon after, a brick with a floppy disk taped to it flies in through the window. Jake stretches over and asks Finn if he ordered a brick but he replies no. They then pop the disk in to find a disturbing video of a woman gagging herself with her own hair. Grossed out, Finn screams at Jake to "escape", but when he hits the button, a glitch comes out of the computer and Finn and Jake freak out and rush to the Candy Kingdom.

The scene has Princess Bubblegum watering plants, then Ice King flies over, greeting her and he reminds her of something she said last summer about dating Ice King only if he was the last person on Ooo. She doubts that she said that, and soon enough Finn and Jake come running to Princess Bubblegum, nearly freaked to death. Ice King asks them if they're having any computer problems. Then, he tells them about the glitch, saying that it exists within the universal source code; Finn exclaims to Ice King to stop talking like a nerd and tell it to them straight. Ice King simplifies his explanation: if the glitch does its work it will delete everything except him and Princess Bubblegum. Ice King vanishes, saying that he'll prepare for his "date." Donut Guy comes out running and shouting and has some kind of glitch on part of his head. Finn says that he and Jake will take care of everything; Princess Bubblegum then pulls out a gun and said that she will take care of this too and they run off.

Finn and Jake start to save the Candy People. Finn starts by carrying Mr. Cupcake, but he ends up getting deleted. Finn freaks out and tells Jake to help him. Jake starts to calm Chocoberry, but her arms and legs fall apart then get deleted. Finn then again tries to help Sugar Cube, but he declines his offer as he saw what happened to Mr. Cupcake when Finn picked him up, then he gets deleted. Finn then says that the things they were doing were not working and they need a plan, but Jake promptly falls asleep for 52 seconds to dream of a plan. When Finn wakes him up, Jake explains his dream plan to Finn. He says that the things he was saying was not good enough for a plan, but Jake intends to finish it. Upon explaining this, Finn panics, but Jake says that they should talk to the glitch like in his dream. Finn agrees and picks up a part of a deleted thing and asks if it can help them, but it replies, "I can't help you goofballs;" however, Finn and Jake can't understand what it says since the letters are backwards (they are standing behind the message). Jake tries to read it and as Finn finds a way out, Jake thinks he has broken the code, but Finn says that they don't have time for it and they enter the way Finn found.

As they enter, Jake announces that the place they have entered is the universal source code. Finn then sees Princess Bubblegum and Ice King inside a big block of ice. Jake starts to wander around and sees two hexagon shapes with a snake and a spider in it, and it goes to a scene where a spider and a snake are about to fight. Jake holds one of the hexagons and places one of its edges next to another; upon doing so, the two shapes combine and the snake and spider are transformed into a spider-snake hybrid. Finn tells Jake not to touch anything because the hexagons are the building blocks of the universe. Jake says that he wants to find and fight the Glitch. Upon finishing his sentence, he wraps himself up and shakes in fear. Finn asks Jake what the matter is; Jake then points out the Glitch, which is seen eating various hexagons from the source code, one of them being Princess Bubblegum's chair.

The next part goes to Princess Bubblegum where she is reloading her gun with tranquilizer darts, and her chair suddenly disappears and falls on the ground. When she falls, Ice King enters. Princess Bubblegum gets up, points the gun at him and asks him to give her the antivirus or she will shoot him with her Candy Horse Tranquilizer, but he says that he even brought her a box of chocolates (among other things); he tastes it and tells her that it is still good, visibly disgusted. He then throws away the box as it glitches up. Ice King starts talking about the promise she said about dating him is he was the last person in Ooo, and at the end of each of his phrases, Princess Bubblegum shoots him with her gun as he slowly passes out, but the darts on his face and the gun get deleted. Princess Bubblegum then says that even though she did promise, he is not the last person on Ooo because she is still there, then she starts kissing her left hand. Ice King tries to get her to kiss his hand, too, but she refuses.

In the source code area, Finn is pulling Jake's hand, telling him to pull it together. Combined bits of hexagon shapes with Jake's body parts are shown, and the Glitch removes Jake's right arm. Finn, who is still pulling Jake's arm, notices that his arm is unattached to him. Jake says with a disappointed tone that he and his arm had so many good times together. A montage of Jake's memories with his right arm is shown. Jake says that he would defeat the Glitch to avenge his right hand. They both charge toward the Glitch, but Finn halts as his body starts to glitch up.

Ice King makes ice sculptures of himself while Princess Bubblegum still kisses her palm. Ice King looks at her then when he turns around, Princess Bubblegum says, "No," to her palm; Ice King smiles, then she kisses it again. Outraged, Ice King says that he's trying to be nice to her and she could at least make the best out of their situation. Princess Bubblegum stands and kneels to him. Ice King thinks she's praying to him and says he's "into this," but she lifts his robe and ties it. He says that he is still "into this," then she pushes him down, and he says again that he's "into it." She stomps on his head and shouts that he give her the antivirus and steps on his head again, but Ice King can't give it to her because he didn't make one. He then says that the Glitch will delete everyone until they were all that is left. Princess Bubblegum hopes for Finn and Jake's success.

Finn is being carried by Jake with his sword in his mouth. They figure out a plan to defeat the Glitch. One second later, they arrive in front of the Glitch. Finn and Jake start to fight it. Jake uses Finn's head to slice the Glitch, but instead a mouth forms that eats the sword and Jake's body suddenly gets deleted. Finn says that they need to get the building blocks out of the Glitch's stomach, then Jake remind Finn of the video they saw of the girl gagging herself with her hair. Jake removes Finn's hat and starts biting Finn's hair. The Glitch, being grossed out, throws up all of the building blocks that he ate from the universal source code, and as he moves far away, some random scenes appear.

Everything that was deleted returns; Finn and Jake celebrate. Ice King is shocked, then he suddenly gets stuck in the side of a reappearing house. Finn and Jake walk in the Candy Kingdom as they observe that everything is back to normal. The Donut guy comes running and shouting that his face is back to normal. Finn asks him if he knows where Princess Bubblegum is, and he shouts that she's in Ice King's castle.

The scene then goes to the Ice King's castle where Princess Bubblegum, who is still unaware that everything was back to normal, angrily beats Ice King's computer with a bat. When Finn and Jake arrive, Princess Bubblegum greets them with a hug. Then the hand Princess Bubblegum was kissing earlier and Jake's arm start kissing, saying that they missed each other. Finn interruptingly coughs and asks where the Ice King is; he and Jake say that they want to "kick his boingloings." Ice King is still stuck on the side of a house, asking where everyone is. The spider-snake hybrid which Jake created starts biting the Ice King's face then the episode ends.

Major characters

 * Finn
 * Jake
 * Ice King
 * Princess Bubblegum
 * The Glitch

Minor characters

 * BMO (cameo)
 * Candy People
 * Sugar Cube
 * Chocoberry (cameo)
 * Donut Guy
 * Mr. Cupcake (cameo)
 * Candy Cane Guy(cameo)
 * Gumdrop Lass 2 (cameo)
 * Root Beer Float (cameo)
 * Candy Corn (cameo)
 * Snail (as a piece of the universal source code)

Trivia

 * This episode features a modified CGI version of the opening sequence, making this the first episode to contain a modified version of the opening sequence since the two gender-flipped episodes ("Fionna and Cake" and "Bad Little Boy").
 * Finn seems to be using a different sword in this episode.
 * The Glitch resembles the Ice King's head.
 * Finn's hair seems to have regrown to the same length from when it was first shown. When they get back to Ooo, it appears the same length as the Mirror Finns in "Gotcha!"
 * At the start of the episode, when Finn and Jake are making an animation, Ice King has spiders and a snake on him. Later in the episode, Ice King is attacked by a spider-snake hybrid.
 * Finn is slightly taller than usual in comparison to Princess Bubblegum.
 * Finn involuntarily punches himself after complaining about the animation process and insulting animators in general. This implies the show's animators heard him, subsequently breaking the fourth wall.
 * When Finn is looking at the source codes for Princess Bubblegum, Ice King and their crowns, there's one that seems to correspond to Lumpy Space Princess.

Cultural references

 * Some of Finn's expressions are widely used Internet emoticons.
 * One of them is a widely used emoticon in Japan: ´Д｀ and  T_T
 * The video of the girl gagging herself with her hair is an actual video by David OReilly, available on his YouTube.
 * The computer used by Finn and Jake resembles one of the earliest Apple Macintosh Computers.
 * Similarly, the media player used to play the video mimics that of the iTunes dashboard.
 * The disk that Finn and Jake receive from the Ice King is called a floppy disk, which is a nearly obsolete external data storage device. More specifically, it resembles a 3 1/2-inch floppy disk.
 * The Ice King being stuck in a wall is a reference to video games, where "glitching" commonly occurs, on many occasions causing one form to be stuck inside other forms, such as a person in a wall.

Episode connections

 * The Sugar Cube guy calls Mr. Cupcake Todd. This may be a reference to "Video Makers" where Mr. Cupcake plays the role of Todd Johnson in the movie.

Errors

 * When Princess Bubblegum goes to hug Finn and Jake, the back of her hair is colored red.
 * Mr. Cupcake is much smaller than his previous appearances.

Production notes

 * This is the first Adventure Time episode to be released on April Fool's Day.
 * This episode, like "Guardians of Sunshine," stands out as it features the utilization of CGI animation. Also like "Guardians of Sunshine," it does not feature the words, "Adventure Time presents" on its title card, and the opening credits are given an episode-themed style. Unlike "Guardians of Sunshine," this episode has no 2D animation whatsoever, making it the only completely CGI-animated episode.
 * This is the first episode to have a trailer that does not have any clips from it in it; instead it's clips from other episodes saying the following: "Warning, we can't show you anything at all from the new Adventure Time. It's just too crazy, man! Ha, hahahahahahaha! Yeah, get your eyeballs ready for the most amazing Adventure Time you have ever seen with your eyeballs, but, um, we can show you this scene from the new Regular Show."
 * This is the first episode to be written and directed by one person.
 * This is the first episode not to have a story co-written by Pendleton Ward.
 * This episode was leaked before its intended airdate.
 * The outro music during the credits is an 8-bit song called "About That Time". This song was made specifically for the episode by an artist known as Flying Lotus.  The credits were not shown during the episode's airing.
 * This is the first episode not to feature "Island Song" during its credits.