* ActorAllusion:
** Vexen. Who would've guessed that [[Manga/{{Bleach}} Uryuu Ishida]], of all people, would become a mad scientist? Captain Kurotsuchi must've rubbed off on him.
*** Let's see, a nice person who became an [[SmugSnake Smug]] {{Jerkass}} and an [[InsufferableGenius Insufferable]] [[EvilGenius Genius]] after being corrupted by the powers of darkness. Sounds like [[Anime/DigimonAdventure02 Ken Ichijouji]] after he became the Digimon Emperor.
** Larxene shares many similarities to [[Anime/NeonGenesisEvangelion Asuka]], basically sharing her bitchy attitude but with fewer redeeming qualities and an even more damaged psychosis. Tellingly, [[WordOfGod Nomura]] said that Larxene's voice was the first one cast for ''RE:Chain of Memories'' and that Creator/YukoMiyamura was always his personal choice.
* DawsonCasting: In the remake, Sora is supposed to be fourteen at this point like in ''VideoGame/KingdomHeartsI'', yet the voice of Haley Joel Osment sounds nothing like a kid anymore.
* FanNickname: The [[spoiler:Riku Replica]] is occasionally referred to as "Repliku". It's even his official name in the D-Report in the German version.
* FlipFlopOfGod: Nomura stated in an interview that Nobodies do not age (with the exceptions of Roxas and Naminé). ''VideoGame/KingdomHeartsBirthBySleep'' appears to contradict this with Ienzo, who was in his early teens when he became a Nobody yet appears in his 20s as Zexion.
* MarthDebutedInSmashBros:
** The Diamond Dust and One Winged Angel Keyblades are in this game. They actually came from ''Final Mix'', which nobody outside of Japan saw without importing it (at least until 2013 and the ''HD I.5 [=ReMIX=]'').
** The Neoshadows, who only showed up in the original game in the secret ending, but were limited to a secret cutscene, and similarly to the above Keyblades were introduced as actual enemies in ''Final Mix''. They return in this game.
* NoExportForYou: Europe and Australia had to wait nearly five years later when [[RemadeForTheExport the game was remastered for the PlayStation 3]].
* TheOtherDarrin:
** Every Organization member except Axel got a different and professional voice actor once they appeared in the (almost) fully-voiced UsefulNotes/PlayStation2 remake.
** In the ''Re:Chain of Memories'' version, Alyson Stoner plays Kairi instead of Hayden Panettiere.
* RelationshipVoiceActor: In ''Re:Chain of Memories'', Kairi and Naminé, who are essentially two halves of the same whole, are voiced by Creator/AlysonStoner and Creator/MeaghanMartin respectively. Those two also played archenemies in ''Film/CampRock''. Make of that what you will.
* WhatCouldHaveBeen:
** Deep Jungle was intended to have made a return, but it had to be axed because Creator/{{Disney}} lost the copyright to ''Literature/{{Tarzan}}''. All that's left in the game is the card for the King of the Jungle Keyblade, albeit DummiedOut.
** The Dive to the Heart was planned at some point. It presumably would've served as the gameplay tutorial, which is instead a normal conversation and fight in Traverse Town.
** Marluxia was originally planned to be female, hence his pink hair and feminine appearance. It was decided that having the only 2 female members of the Organization [[spoiler:conspire to forcibly overtake it]] had too many UnfortunateImplications, so the gender was changed.

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