* ActingForTwo: Susanne Blakeslee voices [[Disney/SleepingBeauty Maleficent]], [[Disney/SnowWhiteAndTheSevenDwarfs the Evil Queen]], and [[Disney/{{Cinderella}} Lady Tremaine]].
* {{Blooper}}: Before fighting the Unversed alongside Mickey in Radiant Garden, if you look carefully behind Aqua, you can see a second Kairi right behind her. This was rectified in ''HD 2.5 [=ReMIX=]'' version.
* CastingGag: Master Eraqus is voiced by Creator/MarkHamill, while Master Xehanort is voiced by Creator/LeonardNimoy, thus making their conflict one of ''Franchise/StarWars'' vs ''Franchise/StarTrek''. WordOfGod is that this was fully intentional.
* ExecutiveMeddling: Two changes were made to a couple story endings because the producers thought the original plans ended on notes that were too depressing. The Final Episode was originally part of Aqua's story but split off into its own scenario, while the scene where [[spoiler:Ven is absorbed into Sora's heart]] was given a framing scene with Sora and Riku on the beach.
* FanNickname:
** [[spoiler:Terra-Xehanort]] is often referred to as [[spoiler:Terranort]].
** The [[spoiler:Reunited Ventus and Vanitas]] is sometimes called [[spoiler:Venitas]].
** Before names were released, Master Xehanort was referred to as OBM (Old Bald Man; in the vein of BHK/Blond-Haired Kid for Roxas). When his name was released, we got affectionate nicknames such as Baldinort, Baldsem, Geezernort, Oldynort, and Grampinort.
** [[spoiler:There's the CaptainObvious-styled Evil Sora for Vanitas. The epilogue also gave birth to ''KH'' Jesus for [[MessianicArchetype Sora]].]]
** As well as [[spoiler:Jesusora]].
** A less common one for Vanitas: [[spoiler:Soranitas]].
** Red Eye and Hunter of the Dark for the [[spoiler:unnamed Heartless that serves as the boss of the Secret Episode, later given the canon name Dark Hide]].
* FanTranslation: With the original Japanese PSP release of the Final Mix version of this game. Like ''KHII FM'', ''BBS FM'' was translated to English, this time thanks to Key To Truth. You must patch the game itself in order to play it in English, which you can do with either an ISO (for Emulation) or with an actual game cartridge.
* IKnewIt:
** [[spoiler:Terra turns into Xehanort!]]
** [[spoiler:Ven becomes a part of Sora.]]
** [[spoiler:Sora's gonna save Terra, Aqua, and Ven from their fates.]]
** [[http://www.khwiki.net/Forum:Armored_Xemnas_-_Keyblade_Warriors On February 2009]], a troper speculated the possible connection between the armor Xemnas wears in ''Kingdom Hearts II'' and the armor the protagonists wear. [[spoiler:That armor is Xehanort's Keyblade Armor that he wore when he was younger.]]
%% ShoutOut isn't Trivia. Don't put it here.
* NamesTheSame: One of the {{Bonus Boss}}es in the ''Final Mix'' version, No Heart, shares his name with an antagonist from ''Franchise/CareBears''.
* PlayingAgainstType: Creator/LeonardNimoy, best known for playing a [[TheStoic stoic]], [[TheSpock heroic character]], plays a hammy villain here (although he still does keep many traits of TheSpock).
* SerendipityWritesThePlot: The secret endings of ''VideoGame/KingdomHeartsII'' that tease this game show the three protagonists wearing armor with capes. The capes were intended to be in the final product from the start, but had to be removed because their animations caused FPS issues during multiplayer.
* TheOtherDarrin:
** Bret Iwan replaces the late Wayne Allwine as Mickey. Surprisingly averted by Chris Sanders, who still reprised his role as Stitch despite [[WesternAnimation/HowToTrainYourDragon now working for]] Creator/DreamWorksAnimation, Disney's primary rival in animated films, following behind-the-scenes conflicts on ''Disney/{{Bolt}}''.
** In the Japanese version, [[Disney/PeterPan Captain Hook]] is voiced by Naoya Uchida instead of Chikao Otsuka, presumably because the latter voice actor was also voicing Master Xehanort.
* TalkingToHimself:
** Averted in the case of Captain Hook due to TheOtherDarrin (Naoya Uchida, who in fact is the usual Other Darrin for the Japanese Hook); in the rest of the series and in the Japanese dub of ''Disney/PeterPan'', Hook is voiced by Creator/ChikaoOhtsuka. Ohtsuka's in this game, but is playing Master Xehanort. And even if Ohtsuka did voice Hook here, the pirate and Master Xehanort do not cross paths anyways.
** Played straight in the English dub by David Ogden Stiers, who plays two of the seven dwarfs (Doc and Happy); Russi Taylor, who plays Minnie Mouse, Huey, Dewey, and Louie, as well as the Fairy Godmother and Drizella (though the two don't have any scenes together); and Creator/JimCummings, who plays Pooh and Tigger. And that's just naming the characters who share worlds together! The actors mentioned (and a few not mentioned) play other characters as well, though those characters aren't even in the same world as each other.
* ThrowItIn: [[WordOfGod According to]] Creator/TetsuyaNomura, [[spoiler:the reason Vanitas looks like Sora was because his Japanese voice actor had always wanted to play the role of a villain]].
* WhatCouldHaveBeen:
** Nomura considered showing Leon and Cloud's past in the game. He decided against it because Radiant Garden was already showing the past of seven Organization XIII members, so including the ''Final Fantasy'' characters on top of them would have overloaded the world with too many characters.
** A world based off of ''Disney/TheJungleBook'' world was going to be featured, but was pulled out. It was likely cut due to legal issues with the late Louie Prima's estate, as the character King Louie is a caricature of him.
** Laguna from ''VideoGame/FinalFantasyVIII'' was meant to appear as the head of the Mirage Arena, but was kept out due to his appearance in ''[[VideoGame/DissidiaFinalFantasy Dissidia 012]]''.
** Pleakley would've made an appearance in Deep Space.
** The Blob Mob was originally a boss, but it was reworked into a normal enemy due to issues with how many bosses were in the game.
** The "Birth by Sleep: Volume Two" secret ending of ''Final Mix'' hints at a sequel for the PS Vita, though it was axed because the producers thought that there were too many portable games in the franchise. Ideas from the proposed sequel are present in the ''2.8'' complitation.
** The first trailer shown at Jump Festa 2008 had a lot of scenes that weren't in the final game, or took place differently. Those scenes include Terra thanking Ventus for saving him from an unspecified incident at the Maw of Hallow Bastion, Ventus talking to Xehanort at the Olympus Coliseum, Terra watching a young Sora and Riku sparring, Terra defending Ventus at the Maw instead of the Land of Departure, and Ventus requesting Terra and Aqua to erase him at the Destiny Islands instead of the Keyblade Graveyard. Most of these can be chalked up to the assets for the new worlds like Land of Departure not being done at the time of the trailer's release.
** This trailer also features a scene where Ventus sees Cinderella arrive at the ball.
** Another Titan from ''Disney/{{Hercules}}'' was considered to be added as a BonusBoss in the ''Final Mix'' version instead of Monstro.
* WordOfGod: According to an interview with Nomura, the encounter with the BonusBoss called Unknown is canon for all of the characters. It's supposed to happen just before each character heads to the Keyblade Graveyard for the final time.
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