A storyboard for a scrapped Season 1 episode “Brothers in Insomnia.”
"What time is it? Seeing 'What Could Have Been in Adventure Time? Yeah, man!!".
- In early versions of "The Enchiridion!", the episode was originally going to be the length of two episodes and would have originally introduced Choose Goose before the episode was shortened and Choose Goose would later be introduced in the season 2 episode "Blood Under the Skin" instead. The episodes title card was also originally much darker with Finn holding a dagger instead of a loaf of bread and Jake's guts being shown. It was likely altered due to censorship.
- According to an interview with Pendleton Ward, the setting of the series was originally meant to just be magical. However, the episode "Business Time" which featured businessmen frozen in ice was when it was decided that the series setting would also be post-apocalyptic.
- In early storyboards of "His Hero", Billy was named "Hogarth", his throne was actually a shapeshifter that he was keeping in check by sitting on it, and Hogarth was originally going to fight the shapeshifter with his survival being ambiguous.
- The original storyboard for "The Duke" has Jake imagining how evil the Duke can be. The Dramatization includes a particularly impressive Hurricane of Nut-Puns by the Duke, which includes "CASHEW LATER, COPPERS!" and "CHESTNUT YOUR DAY, JAKE!". However, this was scrapped for time.
- The Princess Plant was originally supposed to be called the Halo Lily.
- There were some episodes that sadly never made it past storyboard stage, like "Brothers in Insomnia"
, in which Finn and a sleep-deprived Jake try to save a miniature city under their treehouse from a monster, and "The Glorriors", where Finn goes off to impress the eponymous team of veteran heroes. Notably, the plot of "Brothers in Insomnia" was later repurposed into the season 6 episode "Little Brother" with Shelby and his new little brother Kent taking Finn and Jake's place.- "Tower of Bone", a two-part episode for season 1 outline that never made it to the storyboarding stage, featured Finn and Jake facing off against the Lich after he manages to break out of his prison thanks to his minions kidnapping Tree Trunks after she accidentally swallowed the key to it. While it was never made, the idea of Finn and Jake facing off against the Lich after he escapes his prison was reused in the season two finale "Mortal Foley/Mortal Recoil".
- Another scrapped episode would have involved BMO and another robot named CMO and would have explained part of BMO's backstory. While the episode was scrapped, CMO still appeared for a second in the season 5 episode "Puhoy".
- An unnamed season 6 episode which would have been a collaboration with designer/director/puppeteer and MacArthur Fellowship recipient "Basil Twist". While the episode was conceived in 2013, it didn't move past the early development phase.
- An earlier version of the season 8 episode "Cloudy" from the "Elements" miniseries was going to be part of Season 1 before it was altered to fit with the "Elements" miniseries.
- "The Malteser Penguin", an episode written and storyboarded by George Magee and developed around the final few seasons, was originally going to focus on T.V. becoming a detective after his abilities for the jobwere shown in the season 6 episode "The Diary". While the episode was scrapped, T.V. was shown to have become a detective in the series finale "Come Along With Me" and took over Joshua and Margaret's old office.
- A made for TV movie composing of four episodes was originally planned to air as the season finale of season 5 with the ending events of "Sky Witch" originally leading up to it. However, the film was pushed back and eventually canceled. Multiple parts and ideas from the film were later recycled throughout the series such as the beginning of the film being remade into the season 6 episode "Something Big", Orgalorg who was supposed to first appear in the film becoming the main antagonist of the season 6 finale "Hot Diggity Doom/The Comet" and the ideas for Finn traveling through the dead worlds and how they worked being reintroduced in the Distant Lands special "Together Again".
- Apparently, Marshall Lee had lines in "Fiona and Cake", but they were cut for time. Rebecca Sugar wanted him to be voiced by Dante Basco.
- The most unfortunate example yet: Pen had to cut A HIGH FIVE from an episode!! [1] You know what makes this even MORE hilarious? This clip from season four episode ("Five Short Graybles") has a scene entirely dedicated to awesome high-fives.
- The Lich was going to be known as the Lich King until Blizzard supposedly forced them to write around trademarks, and he went through two◊ different◊ redesigns before settling on the final one.◊ During his Early-Bird Cameo, he's referred to by his original name.
- Tom Waits was Ward's original choice for the Lich, but instead they got Ron Perlman. Both are known for their signature gravelly voice.
- The series was originally to be on Nickelodeon.
- The original ending of "Sons of Mars" would have shown Death transporting Lincoln back to Ford's Theater before fading to black with the sound of the gunshot from John Wilkes Booth. The final version has a gunshot, but no Ford's Theater, implying but not making explicit the events shown in the storyboard.
- There were also several changes to "The Lich". For one, Prismo is called "The Almighty Grob", but more importantly the Lich would've been possessing Billy instead of having killed and replaced him, and Booko would have revealed that Finn's human dad was a hero who was wrongfully imprisoned in an impossible-to-escape dimension—with the implication that Billy put him there—and is still fighting the other inmates. This ties into several examples of The Artifact. In the actual series, "Grob" refers to a powerful (but not all-powerful) magical being from Mars (full name Grob Gob Glob Grod). This storyboard also reveals that Finn never realized that he was adopted (with a Lampshade Hanging on the ridiculous levels of Idiot Hero that would come along with this notion), which is obviously not the case in the series and the Lich would have instead offered to help Finn learn what happened to his real parents. Sadly this meant one of the series biggest heartwarming moments ended up being cut as well.
- "Heat Signature" was supposed to air the week before the two part season finale "Mortal Foley/Mortal Recoil", but ended up airing the week after due to problems with Cartoon Network the day it was supposed to air. The writers for the series still consider the two parter the season finale.
- Princess Bubblegum was supposed to stay 13 for a few more episodes before "Too Young" released.
- According to Jesse Moynihan, Lemongrab was not originally a socially awkward, dysfunctional, brain-damaged, unadjusted Jerkass Woobie in the original outline. He was originally conceived by Pen to be a one-shot, one-dimensional Jerkass "like Xergiok." However, Jesse stepped in, and decided to give Lemongrab the puzzling amount of depth he has, by making him "weird, isolated, angry, off-putting, with an inability to read social cues." Part of Lemongrab's appeal appears to be his many woobie-ish and sympathetic traits. If Jesse hadn't fleshed out Lemongrab's character, LG wouldn't have the zealous fanbase he has, and he probably wouldn't have been considered to make a return in the series after his exit from "Too Young", and people would've remembered him solely for torpedoing the Finn/PB ship instead of a memetic Ensemble Dark Horse who launched Justin Roiland into the mainstream and helped get Rick and Morty off the ground.
- During the episode "Simon and Marcy", Marceline was originally supposed to be sick to the point of nearly dying, with Simon looking for medicine rather than soup. This was changed as Cartoon Network executives were concerned this was too dark and potentially explains some of the episode's more absurd elements:
- The Soupery is supposed to be a pharmacy with rows of goods and a greeting cards section, hence why Simon would think to look for medicine there.
- Simon mistakes the Clambulance for an ambulance (with medicine inside) as the first two letters of the name are covered up by grime.
- The episode "Betty" was supposed to be a double episode, but there was already a double episode in production and Huntress Wizard appeared in a 30 second scene but it was cut for unknown reasons, possibly time reasons.
- Based on the production code for season 3 and 4 episodes being the same, it's implied that both seasons were originally produced together as a single season before it was split in half.
- According to Jack Pendarvis, Stephen King was briefly considered as a voice of Root Beer Guy before he voiced the character himself.
- Toronto was going to appear in Apple Wedding, where he catches Princess Bubblegum rooting around in the King of Ooo's things, and she throws him in a suitcase to keep him from interfering in her investigation. He makes his debut in Gold Stars, where he's a lot more sinister.
- At the end of "Hot to the Touch", Finn and Flame Princess were supposed to kiss instead of hug, but this was saved for "Burning Low". It's perhaps this reason that the latter episode is the highest-viewed episode in the series (at 3.5 million viewers, beating the previous 3.3 million record set by "Fionna & Cake").
- The season 5 episode "Be More" was originally planned to be developed during season 3 before it was moved to season 5 instead.
- According to Kent, Pendarvis and Ghostshrimp, if the series were to be renewed for a Season 10, there would be some episodes focused on Susan Strong, Minerva and Sweet P, as well as giving more development for Gumbald.
- Notably, the reveal that Prismo was the true creator of Fionna and Cake and that he was the one that beamed their universe into Ice King's head was originally planned for the scrapped season 10. However, it was later reworked into the Adventure Time: Fionna and Cake miniseries.
- The four parter series finale was originally a four parter season finale with a completely different plot: it would focus on Finn meeting Gumbald and some weird people. It was supposed to take place right after an earlier draft of "Gumbaldia" and mole people would have played a role in it with their existence being foreshadowed in "The First Investigation" when Jake meets one of them. The events of this finale would lead to a Season 10, if the series hadn't been cancelled by CN.
- According to a member of the AT crew, Huntress Wizard wasn't meant to have another major appearance outside of a few cameos after "Flute Spell" and that the Finntress ship wasn't going to be brought up again. However, they changed their minds and Finntress was made official during the final season, albeit without a conclusive note.
- Finn and Susan Strong were originally meant to be siblings, according to Patrick McHale. The original idea was that Finn and Susan ended up being separated from their parents in the middle of the ocean, washing ashore on Ooo in different locations. While Susan was found and raised by the Hyoomans, Finn had a traumatic experience as the ocean tossed and turned him before arriving on Ooo, which was also the reason for his fear of the ocean.
- In the promo art for "I am A Sword" showed Penny from "City of Thieves" fighting Finn after stealing the Finn Sword. In the actual episode however, Bandit Princess takes Penny's role instead since Penny's voice actress was likely not available at the time to record her lines in the episode.
- The Adventure Time: Distant Lands episodes, "BMO" and "Obsidian" were two of multiple miniseries ideas pitched by Adam Muto towards the end of the show's original run, as the three previous miniseries were well-received by both fans and general audiences. Cartoon Network liked the ideas, but there was no desire to make more Adventure Time television content prior to WarnerMedia's plans to create HBO Max.
