Tetsuya Nomura confirmed that the worlds of The Lion King (1994) and The Nightmare Before Christmas (1993) will never be used again. Later at the trailer for E3 2018, it was revealed that Simba will be returning as a summon, similar to Kingdom Hearts (2002).

Sora recognized masked Vanitas, but was shocked by his face when the mask broke. He saw Vanitas unmasked in the last game, so it's impossible for Sora to react surprised.

In 2020, an extended DLC pack known as "Kingdom Hearts III Re Mind" was released, which included additional story material and other additional features similar to the Final Mix versions from some of the previous games. While this was paid DLC in its original release on the PlayStation 4 and Xbox One, in the later releases on the PC and Nintendo Switch (via Cloud) it was included with the game, which for the latter release resulted in a new title to represent both games "Kingdom Hearts 3 + Re Mind".

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