The Dark Phoenix (4): The Fate of the Phoenix - S3-E14
Continuity mistake: Professor X's usual hoverchair was destroyed by the Dark Phoenix in the previous episode, so the Shi'ar gave him a new one to use on their starship. However, when Professor X is lamenting over the X-Men's imminent defeat against the Shi'ar Imperial Guard, he is back in his original hoverchair. Towards the end of the episode, he is back in the Shi'ar hoverchair. (00:04:10 - 00:13:15)
The Dark Phoenix (4): The Fate of the Phoenix - S3-E14
Continuity mistake: When Gambit says to Wolverine "Gambit will be ready," his pants are light-blue colored. A couple of shots later, they are back to being their usual black. (00:05:30)
The Dark Phoenix (4): The Fate of the Phoenix - S3-E14
Continuity mistake: After Storm rescues Gambit from falling to his death and they fly outside, when the shot changes they have literally appeared out of thin air. (00:10:30)
The Dark Phoenix (4): The Fate of the Phoenix - S3-E14
Audio problem: When Cyclops says "Then why not trust us to deal with Jean?" his mouth is completely closed. (00:03:10)
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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