Continuity mistake: When Storm defeats Callisto in combat, Sunder and Tar Baby are in the far background, standing near a tunnel opening. When the shot changes, they are now standing in front of some machinery. (00:18:58)
Continuity mistake: When Xavier is talking to Jean and Cyclops at the end, the three of them, along with Storm, are all to the left of the bed Gambit is lying on, with Storm being behind Xavier, over his right shoulder, and a piece of machinery behind her. When the shot changes, it is a closeup of Xavier, and neither Storm, nor the machinery are visible over Xavier's shoulder. When Jean and Cyclops leave the room, Xavier is now at the foot of Gambit's bed, several feet away from Storm. (00:20:08 - 00:20:32)
Answer: Chris Potter, the original Gambit voice actor, did indeed quit the role in the 4th season. His last episode was The Phalanx Covenant Part 1 so it seems reasonable that Fox would limit the use of the character even though it was recast. It doesn't appear that Potter left the role due to animosity, he stated in an interview that he wished to play Gambit in the first live action X-Men film.
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