* BeamMeUpScotty: Without going into spoilers, the game's famous MemeticMutation is actually "Who else will I have ice cream with?", not "who will I eat ice cream with?"
* BillingDisplacement: Mickey's presence on the cover only serves to remind players of the Disney elements in the game, because aside from being playable in mission mode, he only appears in one short cutscene and doesn't even meet the hero.
* CreatorBacklash: Tetsuya Nomura profusely apologized for the movie in the ''I.5 HD [=ReMIX=]'' collection not adapting any of the battle scenes from the game, noting that the transition between [[spoiler:Xion challenging Roxas and then collapsing in defeat]] was pretty terrible and awkward. The cinematics for the ''Re:coded'' movie in the ''II.5 HD [=ReMIX=]'' collection had short battle cutscenes to remedy this, and the aforementioned example from the ''358/2 Days'' movie was amended in 2017 for the [=PS4=] version.
* NewWorkRecycledGraphics: The [=FMV=] cutscenes reuse models from ''VideoGame/KingdomHeartsII'', and a couple cutscenes are ripped directly from that game.
* TheOtherDarrin:
** DoubleSubverted. Although Christopher Lee came back to voice [=DiZ=] in this game after Corey Burton voiced him in ''Re:Chain of Memories'', he was replaced again in the 1.5 HD Remix due to added scenes and to keep consistency between the voices.
** Similar to the above, the 1.5 HD Remix extended Mickey's sole scene with Riku, but because Wayne Allwine passed away shortly after recording the original, Bret Iwan had to take over.
* UpdatedRerelease: {{Averted|Trope}}: Notable, as this is the only game in the series so far not to be remade or given a [[NoExportForYou Final Mix]]. Its cutscenes were redone with the series' traditional [=PS2=] in-engine graphics for ''Kingdom Hearts HD I.5'', however.
* WhatCouldHaveBeen:
** A beta version of the game from 2006 had a MP gauge, suggesting that ''VideoGame/KingdomHeartsII'''s magic system was considered instead of the panel-based one in the final product. There is also a bar labeled "LM", likely a Limit meter that charged up before letting the player use a LimitBreak instead of having it be dependent on how much HP the character has left.
** Luxord's Mystery Gear weapon was originally meant to be [[http://snowpirateroy.deviantart.com/art/Mystery-Gear-References-152647191 dollar bills]].
** A world based on Pleasure Island from ''Disney/{{Pinocchio}}'' with a WhatMeasureIsANonHuman-centered plot was planned, but it was scrapped due to space limitations. Some ''Pinocchio'' character sprites [[DummiedOut are tucked away in the game files]], and aspects of this idea were later used in ''VideoGame/KingdomHearts3DDreamDropDistance''.
** DummiedOut sprites of Megara and Hades indicate that they were planned to show up in Olympus Coliseum.
** A full remake was considered to be made as part of ''[[CompilationRerelease Kingdom Hearts HD I.5 Remix]]'', gameplay and everything, but was scrapped due to time concerns.
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