After Fionna and Cake accidentally break Prismo's remote, the group are stranded in a desolate land where BMO and "Jerry" are the only residents left. As they resort to desperate measures to escape and Simon opens up to Fionna about his past with Betty, Scarab has a chat with his boss.
Tropes Include:
- After the End: The Extinct World the trio lands in is revealed to be a dimension where the Lich succeeded in exterminating all life. In an instant, every living person turned into a skeleton, leaving only a desolate wasteland inhabited only by BMO and a nonfunctional Lich.
- Be Careful What You Wish For: This version of the Lich has gotten his wish to eliminate all life… and is filled with ennui since he no longer has a purpose.
- Call-Back:
- Multiple relics shown in Simon's powerpoint are the Armor of Zeldron from "Blood Under The Skin", the Wand of Dispersement from "Sons of Mars" and "Skyhooks II", the Lamb Relic from "Beyond this Earthly Realm" and The Enchiridion with he episode revealing how Simon obtained it with Betty's help and the picture of him holding it in "I Remember You" as well as Betty attempting to leave for the outback which she mentioned in "Temple of Mars".
- The end of the episode reveals the universe our heroes arrived in to be one created by the Lich's wish to end all life in existence from "Finn The Human". Much like Jake's wish didn't undo the existence of Farmworld, this world also continued to exist.
- The Lich calls Simon "ice wizard" instead of Ice King, as he did in "Mortal Recoil" when he possesses Princess Bubblegum
- Cassandra Truth: While the audience members present during Simon's presentation besides Betty don't believe him about the magic artifacts and their existence, people who watched the original series know that he is actually correct about all of them existing.
- Cerebus Retcon: It turns out the Lich's wish for the extinction of all life in "The Lich" wasn't really undone in "Jake the Dog". The reality his initial wish created still exists.
- Cliffhanger: The episode ends with Simon doing the same ritual from the start of the series. Fionna and Cake jump back into their world inside his mind while Scarab readies his blade. Only when Simon says goodbye he remembers Betty saying goodbye and a new portal opens up causing Simon and Scarab to fall in. A portal straight to Golb. Looks like Simon will meet with Betty again after all…
- Embarrassing Old Photo: A few videotapes of Simon’s antics as Ice King are found at the remains of the Ice Kingdom. BMO plays them for Fionna showing her how he acted in this state and his sudden death. This becomes one of the main reasons Fionna changes her mind about wanting to change Simon back.
- Exact Words: The Extinct Universe is created by The Lich’s wish to end all life. So robotic entities, such as BMO, do not count, since they’re technically "not alive".
- Five-Second Foreshadowing: When Simon, Fionna, and Cake enter the domain of "Jerry", the light radiating from within the room has a sickly green color. The same lighting commonly associated with the Lich. A few seconds later, Simon sees that "Jerry" is none other than the Lich himself.
- Freeze-Frame Bonus:
- If one looks closely at the end of the videotape of the local Ice King that the heroes find, you can see the moment that he and Gunter are reduced to skeletons by the Lich’s wish.
- When the group leave the remains of the Ice Kingdom, the Ice Crown can still be seen inside the Ice King's drum like in the last video tape with Fionna looking in its direction. This foreshadows her later taking it and hiding it in her bag.
- Internal Reveal: Fionna gets a better view of what the crown turned Simon into, and what Simon would lose if their goal succeeds.
- Ironic Hell: The Lich wished for the destruction of all life in existence where everyone else was dead except for him (and BMO, due to him being a robot). By the time the group find him, not only is BMO dead as well, but The Lich has become a depressed shell of his former self and doesn't even bother trying to kill them.
- Irony: The ritual which summoned Fionna and Cake that Simon performed twice near the beginning of the season failed to bring him to Betty, who was merged with GOLB, due to his inability to stop thinking about the Fionna and Cake series. When he performs the ritual here to return Fionna and Cake back home and return magic to their world, just when he is about to put the crown on his head he ends up recalling a memory of him saying goodbye to Betty at the last second, causing the ritual to open a portal to GOLB, thus unintentionally succeeding in his original plan instead.
- Nothing Is Scarier: In contrast to the prior worlds they've been in, there are no hostile monsters or natives to attack the trio when they warp in there...in fact, there's nothing at all. No animals, no inhabitants, and no growing plant life, with zero clues left behind as to what rendered the place so barren and lifeless. Simon off-handedly mentions their supplies are limited to what they brought with them, and there's a very real danger that they could actually just starve to death in a land that can't provide them anything to eat if they spend too long there. Scarab's ceaseless pursuit of them is even put on hold due to events outside their control, meaning not even he turns up to menace them, and further enhances the desolation of the world. When the trio find the Ice King's old tapes, there's a Freeze-Frame Bonus of him and Gunter turning into skeletons in the blink of an eye just as the recording is ending, with none of the characters noticing and no reasoning provided as to why until they encounter the Lich, making it clear that they were in the universe that the Lich wished for the end of all life in existence.
- O.O.C. Is Serious Business: Normally, the Lich would be ecstatic at the opportunity to kill any living thing if given the chance. However, when the main trio stumbles upon him in his tomb and he has them at his mercy, instead of killing them, he just lets them go and goes back to his catatonic state. This causes Simon to realize they aren't in danger as the Lich is too gloomful to slaughter them on the spot.
- Oh, Crap!: As soon as Simon sees that "Jerry" is the Lich, he freaks the hell out and advises Fionna and Cake to just run. Thankfully, the Lich is too depressed to kill them.
- Plot-Mandated Friendship Failure: Cake seems hostile to Fionna, still upset over her actions preventing her taking the crown from the Vampire King, abandoning the Vampire World, and her involvement in breaking the remote control which reaches its breaking point right after BMO states that he was wrong while under the guise of Princess Bubblegum. Near the end of the episode, Fionna and Cake get into another argument when Fionna realizes the state that Simon would be in when he put on the crown again and Cake not wanting to go back to being a regular house cat again. However, they make up by the end of the episode.
- Sole Survivor: Besides the Lich, BMO is the sole survivor of the Lich’s wish, until he sacrifices himself to help Fionna, Cake and Simon fix their remote control, leaving the Lich as the only "living" being left on the planet.
- Stripped to the Bone: The Lich's wish of extinguishing all life was apparently granted by every living thing being reduced to a skeleton in an instant.
- Take Our Word for It: The audience doesn't hear the conversation Orbo and Scarab have with their boss nor exactly what it was he told them, but whatever he said allowed Scarab to both continue hunting the main trio and not get his legs broken by Orbo.
- Tom the Dark Lord: BMO, out of ignorance or otherwise, has taken to calling the Lich by the name Jerry. This serves to obfuscate the reveal of who Jerry is.
- Uncertain Doom: The fate of other robotic characters in the Extinct World like NEPTR and the other MO robots is never revealed.
- Victory Is Boring: Ironically after finally succeeding in his objective the Lich has become depressed and despondent, unable to even care there is life once again in his realm.
- Wanting Is Better Than Having: This version of the Lich has gotten his wish to eliminate all life, but is left without any purpose as a result, and can’t even bother to kill the heroes when they meet him.
- Wham Episode: The Extinct World turns out to be the same reality created by Prismo granting the wish of The Lich back in "Finn The Human". Because the Lich is too depressed to do anything, Simon uses him as a magic battery and Fionna and Cake are sent back to their world in Simon's head. However, unbeknownst to him, the Scarab had caught up with him during the ritual and was preparing to attack him. Just when Simon is about to put on the crown, he has a memory of Betty saying goodbye to him, causing the ritual to create a portal to GOLB.
- Wham Line: "Shoot, I was hoping we wouldn't have to do this" is spoken by Fionna revealing she had gathered the crown of that universe but hid it as a last resort, not wanting to turn Simon back into the Ice King.
- Wham Shot:
- At the end of the Ice King's tapes, for a split second, he and Gunter are instantly reduced to skeletons, indicating what happened to life in this world.
- Simon, Fionna, and Cake finding "Jerry"—who turns out to be the Lich.
- After Simon and Scarab fall into the portal to Golb, the Lich's green eye changes into red flame with the appearance of Golb.
