Adored by the Network: The show was very much adored (along with Regular Show, Johnny Test and, to a lesser extent, The Amazing World of Gumball) back when Cartoon Network was trying to Win Back the Crowd following its disastrous stint to become a live-action channel. The show would eventually be surpassed by the latter of the four as the network's favorite, and would eventually be dethroned completely by Teen Titans Go!, to the point that the only places the series can be watched are video on-demand, on the official Cartoon Network app, on the DVD and Blu-Ray releases, and on YouTube (if the copyright police haven't taken down the episodes yet). Fortunately, re-runs finally returned on October 25, 2015 in the lead-up to the seventh season. It used to air on Saturday evenings as part of a block called Regular Time Adventure Show (which features new episodes, shorts and reruns of Adventure Time and Regular Show). Eventually, the block was dropped and while Regular Show still got to air a single 15-minute episode right before [adult swim], Adventure Time was pulled entirely. In spite of getting Screwed by the Network for the final years of its run, Cartoon Network aired a marathon of fan-favorite episodes on September 3, 2018 leading up to the series finale. They then proceeded to air reruns of the show, as well as the finale special, every day after its premiere (which was a lot more than what Regular Show and The Amazing World of Gumball got in terms of the channel preparing a special day for its finale, Johnny Test however also got this with Johnny Test-Mas in 2014). This surprised many fans, as Cartoon Network usually only gives this treatment to special episodes of Teen Titans Go!.
One fan made a drawing of a tiny cat assassin named Me-Mow. The creators liked the idea, and thus, the episode "Jake vs. Me-Mow" was born.
Sort of. Liz Prince wrote a 7-page story called "Fruit Salad Days" for Marceline and the Scream Queens Issue 3, in which Lemongrab was the frontman of a punk rock band called "Unacceptable." Liz Prince's idea of Lemongrab having a punk band named Unacceptable was actually re-used for an official Adventure Time game and comics the following year.
Finn's 13th birthday episode first aired, coincidentally, on Pi Day (March 14, 2011) which first Fanon and later Word of God made his birthday.
The Cartoon Network Australia version of Adventure Time has a truckload of stuff cut for objectionable content (mostly innuendo, some rude languagenote rude by the standards of Australian children's TV, and any scene deemed inappropriate for children due to violence, suggestive humor, and glamorizing anything considered immoral or illegal), making a lot of episodes look and sound choppy and incomprehensible.
Cartoon Network Latin America censored and banned a lot of episodes as well.
The UK DVD issues have no special features. The British Season Two DVD had four full episodes missing, including some highly significant ones for larger arcs, and the Season Three DVD leaves out another four. However, in 2019 it was announced that Manga Entertainment were re-releasing the first three series on both DVD and Blu-Ray uncut (as well as releasing the fourth and fifth series)
Banned Episode: The first printing of the eleventh issue of the ongoing comic was pulled from stores at the last minute and pulped - not because of any content in the story itself, but because a house ad for Bravest Warriors showed a character making what was considered to be an all-ages-inappropriate hand gesture.
In Australia, the episodes that aren't aired butchered are merely pulled from rotation (such as "Fionna and Cake" and "What Was Missing" due to many scenes deemed too sexually suggestive). Thankfully, when the series appeared on free-to-air it was screened unedited (though a few episodes were out of order).
The episodes "Wake Up", "Escape from the Citadel", "The Tower" and "Breezy" were banned in several countries (including the United Kingdom and Poland) because of thinly-veiled sexual content and because those were the episodes were Finn loses his arm and copes with the loss. Their absenses have caused several plot holes.
The episode "All the Little People" was banned by Cartoon Network in Latin America for racy content. Furthermore, the episode isn't available legally on their version of Netflix. However, the episode was broadcast uncensored in the free-to-air channels.
The series itself (along with Steven Universe and other shows) got banned in Kenya in 2017 for its depictions of homosexuality and homosexual relationships.
In "The Limit" Jake says he can't blink... and then blinks mere seconds later.
They forgot to put the snail in "Trouble in Lumpy Space" and "Blood under the Skin".
In "Business Time", they misspell Finn's name as "Fin".
In "Reign of Gunthers", Princess Bubblegum says "calvary" instead of "cavalry" at one point, which is more out of character than Finn's malapropism above.
In "You Made Me!", Lemongrab's shoes randomly disappear when he takes out the Sound Sword for the first time.
Cash Cow Franchise: On top of the things listed on the franchise page, it also has various toy and clothing merchandises with more still to come. Even though the show itself doesn't air as often as it used to, it's still having merchandise churned out.
Olivia Olson as Marceline displays her vocal skills in multiple episodes.
The Gender Bending episodes seem built around the idea of having the guest cast sing. Madeline Martin voices Fionna the Human and sings in both episodes, with NPH-as-Prince Gumball in "Adventure Time with Fionna and Cake" then Donald Glover who voices Marshall Lee, sharing a duet and singing to Fionna in "Bad Little Boy".
Jake gets to show off John Dimaggio's beatboxing skills (similar to Futurama) at the beginning of "Conquest Of Cuteness."
Channel Hop: The pilot was created for and aired on Nickelodeon's Random Cartoons. Ironically, as of the third season, Adventure Time is now airing on a Nickelodeon channel in Germany.
The Distant Lands specials will be airing on HBO Max, the WarnerMedia streaming service (it's CN's first major contribution to the service).
"Fionna and Cake" and "A Hot to the Touch" were leaked ilegally on Youtube days before their premiere.
Some members of 4chan managed to leak not only some clips from "The Lich" before its premiere, but also the first two episodes of Season 5, "Finn the Human" and "Jake the Dog".
Some episodes from Season 5, such as "Up A Tree", "Bad Little Boy", "Simon and Marcy", "A Glitch is a Glitch" and "The Party's Over, Isla de Señorita" were all leaked before their respective airdates with the latter episode being uploaded by accident on iTunes.
On December 2013, Cartoon Network listed eight episodes from the sixth season on their website, which not only spoiled the existence of Finn's father, but also revealed that Finn was going to lose his arm.
Weeks before "Breezy" premiered, an annonymous user leaked several animation cells for "Something Big" and "Furniture and Meat" on 4chan, which spoiled Root Beer Guy's death and Finn recovering his arm. Said user also leaked some episode titles, such as "Evergreen" and "Jake the Brick."
On May 2015, Cartoon Network uploaded "Water Park Prank" on their website by accident, several weeks before its premiere.
Thanks to the security breach mentioned above, the majority of the episodes from Season 7, including the "Stakes" miniseries, were all leaked to the public.
Not an episode leak, but a leak nonetheless: on November 2017, a former member of the production crew posted a photo of a shirt on social media. Said shirt contained an official artwork related to the Series Finale, showing Finn, Jake, Fern, BMO, LSP, Princess Bubblegum, Marceline, Normal Man, Ice King, Betty and the silhouette of GOLB.
Creator Breakdown: Pendleton Ward quit as the showrunner during season 5 as he couldn't handle the influx of work and stress which came with running an extremely successful show. He still continued voicing Lumpy Space Princess and helping out with the writing, but his position as showrunner was given to Adam Muto.
According to Ghostshrimp in his podcast, the production crew was expecting Cartoon Network to renew the series for another season while they were still working on Season 9, but the channel cancelled the series mid-production, leaving only four episodes for the crew to work with. These four episodes became the series finale.
Andy Ristaino (character designer) never said that "What Was Missing" was a musical. He said that the episode would kind of resemble one because it has a couple of songs in it.
This was the reason for the whole "BubblegumXMarceline Mathematical" fiasco. Frederator took down the video because it made it seem like the show was openly asking for plot input for further PBxMarcy development and Adam Muto, the storyboard artist and writer of the episode, didn't like the video framing that interpretation as only being romantic.
God Does Not Own This World: Pen Ward may be the main creative force behind Adventure Time, but if we wanna get really technical, Cartoon Network owns the show, not him (though that should be kind of obvious). From an interview:
Pen: I get a lot of emails from people asking, "Can you give me permission to make this?" Well, first of all, I don't own Adventure Time, so I couldn't give permission if I wanted to.
All four console games (Hey Ice King, Why'd You Steal Our Garbage, Explore the Dungeon Because I Don't Know, Secret of the Nameless Kingdom and Finn and Jake Investigations) suffered this due to their publishers lost the licenses. While physical copies can still be bought, both Explore the Dungeon and Finn and Jake Investigations had Downloadable Content (Peppermint Butler, King of Mars and Gunter in Explore the Dungeon, the "Sword of the Dead" (Nintendo 3DS) and the "Artifact Checking" episode (console and PC version) in Finn and Jake Investigations) that can no longer be bought.
The showrunners have stated on multiple occasions that Marceline and Bubblegum's relationship would never be acknowledged in canon out of sensitivity for other countries that don't cotton well to the idea of homosexuality (and often edit or ban episodes that depict it). Come the finale and guess what happens (though that probably hasn't stopped international versions from censoring it)?
"Fionna and Cake" was never aired in France or Belgium.
The DS version of Adventure Time: Hey Ice King! Why'd You Steal Our Garbage?! was never released outside the US. The 3DS version finally came to Europe over a year later, albeit in digital form only. As Video Games Awesome! pointed out, Canada had only just started airing the first season, so there was no reason to release the game. The crew recieved episodes and the game through outside means.
Played straight with Zack Shada. Zack hit puberty and he couldn't get his voice to sound like Finn's anymore, so when the show went from being a Nickelodeon pilot to a Cartoon Network series, the voice director got Jeremy Shada (Zack's younger brother). Now averted with Jeremy, as rather than get rid of him because of his voice changing, the writers incorporated Jeremy's vocal change to Finn's by periodically aging him (by the series finale, he's 17).
Princess Bubblegum is played by Paige Moss in the pilot and Hynden Walch in the series.
In the pilot, Lady Rainicorn was voiced by Dee Bradley Baker and spoke nonsense. In the show, her voice actress is Niki Yang (the same Niki Yang who plays BMO) and the nonsense was replaced with fluent Korean.
Tiffany was voiced by Vincenzo Rauzo in his first appearance in "My Two Favorite People". He has been voiced by Collin Dean in the character's subsequent appearences.
Ghost Princess is played by Pen in "Loyalty to the King" and Maria Bamford in "Ghost Princess".
In the video game, Marceline is played by Jessie Seely instead of Olivia Olson. Granted, the difference is barely noticeable.
In "Davey", to make his disguise more authentic, Finn changes his vocal chords to a more adult tone of Davey Johnson.
In his first appearance, the Cosmic Owl has a feminine-sounding voice provided by Finn's actor, Jeremy Shada. In his next speaking role, M. Emmet Walsh took over the role and gave him a much more masculine, older-sounding voice.
John DiMaggio voiced Jake's brother Jermaine in "Crystals Have Power", but in "Jermaine" he's voiced by Tom Scharpling of Steven Universe.
Huntress Wizard is voiced by Maria Bamford in "Reign of Gunters", but in "Flute Spell", she's voiced by Jenny Slate, fresh out of Zootopia.
Felicia Day replaced Lena Dunham as Betty for the Elements mini-series.
Permanent Placeholder: The main title theme was a scratch recording. Originally played and sung by Pendleton Ward, in the background you can hear storyboard artist Derek Drymon typing on a keyboard and squeaking his chair. Ward attempted to get a better recording of the theme song but couldn't ever capture the feeling quite right ever again, so the scratch recording stayed.
At first, the Ice King seems no different than Tom Kenny's usual characters, until the Christmas Episode "Holly Jolly Secrets" where it's revealed that The Ice King was once a man named Simon Petrikov and that he became the Ice King after wearing a crown that drove him to insanity.
The Ancient Sleeping Magi of Lifegiving is initially pretty similar to Dana Snyders usual unhinged, hammy Cloudcuckoolander characters, but his mental health issues are depicted tragically, and he ultimately comes off as a very lonely and damaged man who desperately wants friends.
Production Nickname: The staff have mentioned◊ jokingly calling the shape-shifter from "Joshua and Margaret Investigates" who turns out to be Jake's biological parent "The Peeper".
Schedule Slip: Season 8 was originally planned to premiere in 2016 alongside the "Islands" miniseries. However, according to an interview with Adam Muto, Season 8 was delayed to early 2017 after the series was announced to end in 2018, in order for the crew to take their time to work on the final season. This decision also delayed the final episodes of Season 7, "Preboot" and "Reboot", to November 2016.
In 2015, the series began getting this treatment for unknown reasons, though the saturation of the schedule with Teen Titans Go! reruns, its age (the series premiered in 2010, and is pretty old by industry standards), or Moral Guardians (the show has had alot of violence, some gore, and a fair amount of innuendo) are most likely to blame. The series wasn't rerun much in 2015, and new episodes are were only advertised online. The situation slightly improved in mid-2016 with better advertising, but reruns were still non-existent, meaning if one missed an episode, they would have to watch online (either through the CN app, on unofficial hosting sites, or outright piracy), or through video on-demand services.
The screwing intensified in mid-late 2016. In September, it was announced the series would end after its ninth season in 2018. Then, the Finn & Jake balloon did not show up in the line-up for the 2016 Macy's Thanksgiving Day Parade, meaning it was retired. And finally, the two-part seventh season finale aired in other countries before the United States, received zero promotion in the US, and was suddenly rescheduled right before its airing, giving it the series' lowest ratings. This treatment of Invisible Advertising continued for Seasons 8 and 9, and a complete lack of reruns (aside from the "Stakes" miniseries airing on the weekend before Halloween due to being thematically appropriate; a regular rerun schedule wasn't re-established until June 2017, when the series began airing in an hour-long block on Mondays at noon) made it very clear that Cartoon Network was working as hard as it could to snuff out what was once its flagship series.
The production team had actually planned for a tenth season, only to be informed that while they were working on the ninth, the network had chosen not to renew it. So season nine had to be reworked to give it an ending, and fanfiction writers were left to tie up the loose ends (mainly the lack of resolution for Finn's love life).
Whenever someone is asked whether Susan is human or not. The answer is usually "Come up with your own conclusion." "Deep Purple" eventually revealed that she's a human with some cyborg augmentation.
The same answer is usually given regarding the relationship between Lemongrab and his clone. Princess Bubblegum and Marceline used to get a lot of this to until Olivia Olson finally just flat out confirmed that they're ex-girlfriends. They can never explicitly say it in the series, though, because the series airs in countries (specifically Russia, The Middle East, most East Asian countries, and Latin America) where homosexuality is, at best, a social stigma seen as highly taboo, and, at worse, a punishable offense. Ornot.
Spoiler: Though the spoilers don't actually happen "in-show". A lot of the season one storyboards could be viewed online before their episodes even aired. But hey, it would be fun to watch the episodes to see if anything got changed.
Pen Ward blatantly mentioned at Comic-Con that Flame Princess would be Finn's new love interest before "Incendium" aired. However, he didn't spoil her destructive personality and only called her "intense" (a word that a member of the audience laughed at). At the same time, he also possibly spoiled the ending of "Too Young" when the Finn/Princess Bubblegum ship was sunk.
TV Guide spoiled the fact that the short stories in "Five Short Graybles" are centered around the five senses (sight, touch, taste, smell, and hearing). It wasn't supposed to be revealed until the end of the episode. It really makes "Huh? You still haven't figured it out?" less funny.
An ad from Gamestop Canada showed some scenes from "The Comet" before the episode aired on North America.
The DVD cover for "Islands" was posted online weeks before Cartoon Network posted the opening on their social media accounts. Said cover also revealed Finn's robotic arm.
A short clip from "Always BMO Closing" was shown in a bumper three months before the premiere of Season 9. Said clip also revealed that Jake returned to his original self, since the last thing AT related CN aired at the time was the "Elements" miniseries.
Cartoon Network itself spoiled the ending of "The Wild Hunt" on Facebook and Twitter hours before the premiere of Season 9, revealing Uncle Gumbald's identity and Fern's new Green Knight look.
Tom Kenny voices both the Ice King and his penguins.
While it's not clear if any of her characters talked to each other, stand-up comedian Maria Bamford has voiced twenty-six voices for the show, even doing male voices such as Manfried in "Slumber Party Panic" and the Butterfly Bandit in "The Other Tarts".
Justin Roiland voices Lemongrab, Lemongrab's clone, and all of their children.
An unusual example. When Adam Muto originally pitched "What Was Missing", he flubbed the original line that read "I'll get your toy back, kid!", and he said "I'll get your kid back, toy!". They thought it was funny that way, so they kept the line flubbed.
In "Goliad", the titular character (voiced by writer GrahamLinehan's daughter) badly flubs the line "I'm Don Juan Cherry Tempo!" but the producers clearly thought it was so adorable and funny that they left it in.
Natasha Allegri, on an ambiguous level. For example, there's all her Bubblegum/Marceline fan art before and after "What Was Missing" when she claimed that she didn't even understand what shipping was. Hell, someone even called her out on it, and she responded, "I've never drawnthem kissing." And later, when someone showed her a picture she drew of PB kissing Marceline, she said, "It doesn't have my signature on it." (That's only because she drew it for 4chan, and she doesn't sign those pictures.) And there's also when she drew this Fubblegum pictureright before "Incendium" aired. And ALSO when she drew Flame Prince just to cause war-shipping in the gender-bent lovers of the fandom.
A lot of the fandom sees the show's writers as this. For example "Fionna and Cake" basically compares the Ice King to fanfic writers. Many fans see "All the Little People" as a Take That! and parody of shippers in general. And then there's the end of "Mystery Dungeon" where Ice King didn't get to make the Fionna and Cake world real, which is what many fans wanted. In particular, many fans advocate a meeting between Finn and Fionna, to the point that the Finn/Fionna ship is rather popular, though many other fans reject the ship for basically being what is referred to as "selfcest". Still others Take a Third Option and make Finn and Fionna long-lost twins.
Seeing as some fans ship the two Lemongrabs together, "Another Five Short Graybles" has the original Lemongrab eat the other, as well as revealing that they view each other as brothers rather than lovers.
Voices in One Room: The cast records their dialogue together in one room, which is rare for an animated show.
Allegedly, Pen stopped answering Formspring questions because he got tired answering the same ones over and over again.
The uproar that happened over the Ship Teasing in "What Was Missing" caused "Mathematical!" to stop producing recaps.
Nat and Pen used to make themselves known on /co/, but they stopped due to... obvious reasons. Nat later came back for the show's second anniversary. She also came back the Sunday night before the season 4 finale.
Lead character designer Andy Ristaino revealed that the Gladiator Ghosts are indeed homosexual and in love with each other after "Morituri Te Salutamus" aired.
Kate Leth draws the Lady Lemongrabs as a couple. In the Fionna and Cake comic book, their relationship is only suggested through (admittedly obvious) subtext. Outside of the issue, though, Leth repeatedly draws the Lady Lemongrabs in obvious romantic scenarios.
Olivia Olson, the voice of Marceline, revealed that someone on the show's crew told her that PB and Marcy used to date, but that they can't outright say it on the show because of Moral Guardians and (most likely) the Russian government. This didn't stop them from going for broke in the series finale and giving PB and Marcy The Big Damn Kiss scene.
Princess Bubblegum is actually made of bubblegum. Princess Bubblegum's composition is actually a plot point in "Mortal Recoil".
BMO is "sexless", being a robot, and also genderless. They have been called masculine or feminine pronouns by different characters. For what it's worth, BMO is voiced by a woman, and the episode title "BMO Noire" uses a feminine spelling for the French adjective; however, that same episode has BMO imagine having a relationship with a female (chicken), while in another they pretend to be a "real boy."
Months after the airing of the controversial, "The Red Throne", the crew confirmed at Comic Con that Flame Princess and Cinnamon Bun are not dating.
Adam Muto finally revealed what was Martin's cosmic crime at the finale's screening: turns out Martin went into space and kept conning people left and right until one of his cons caused some trouble with aliens, which resulted in his imprisonment at the Crystal Citadel.
Kent Osborne and Ghosthsrimp revealed at the Ghostshrimp and Friends Podcast that GOLB is absolutely powerful and the finale didn't show his full potential. They also revealed that Betty has total control of his mind after she fused with him.
Kent and Shrimp also revealed that Fern is still alive and inside the Finn Sword.
As said above, the romance between Finn and Huntress Wizard was originally never meant to be brought up again after "Flute Spell". However, the writers had no plans of leaving their relationship dead in the water either.
Working Title: Many of the episodes have had original titles that were changed. Some examples:
"The Royal Promise" → "Slumber Party Slaughter" → "Slumber Party Panic"
"Meet the Ice King" → "Prisoners of Love"
"Ice King and Son" → "What Is Life?"
"Return to Nightosphere" → "Marceline's Dad" → "Nightosphere" → "It Came from the Nightosphere"
Tree Trunks was based on as well as written expressly for Livingston, who is an old friend of Pendleton Ward's family.
Not so much a person, but a urinal where Penn works was the inspiration for the Cosmic Owl. The light reflects off the very shiny metal urinal and resembles the Cosmic Owl. This strange little tidbit of triva came from a interview with Nintendo Power.