Night of the Sentinels: Part 2 - S1-E2
Continuity mistake: After Cyclops tells Gambit to blow up the fence and Rogue flies into frame, her headband and the patches on her uniform that are all normally black are now red. Additionally, the black encircled X on a red background on the left side of her chest is now a yellow X on a red background. (00:06:35)
Night of the Sentinels: Part 2 - S1-E2
Continuity mistake: When Gambit says "You wanna play with Gambit? Here, take a card!" the glove on his right hand is missing, then is suddenly back on his hand when he says "House wins." (00:05:50)
Night of the Sentinels: Part 1 - S1-E1
Continuity mistake: The Sentinel that is intercepting Jubilee when she is running back home to check on her foster parents is initially following her along the sidewalk from behind, but suddenly catches up to her in a perpendicular path from the street. There are only two Sentinels shown in this scene and the other one caught her from the front as it turned a corner, so it couldn't have been a different one. (00:14:40)
Night of the Sentinels: Part 2 - S1-E2
Continuity mistake: At the end of the previous episode, Rogue says to Cyclops "You look nervous as a long-tailed cat in a room full of rocking chairs," to which he responds, "I just wish I knew what was happening in there." Cyclops then immediately looks to his right and sees military vehicles approaching and says "We've got trouble." At the beginning of this episode, the same scene is shown again, only this time Gambit says "If that was me in there you wouldn't have to worry" before the military vehicles are shown to be arriving.
Night of the Sentinels: Part 1 - S1-E1
Continuity mistake: The position of the police cars around Sabretooth change from shot to shot. (00:01:15)
The Unstoppable Juggernaut - S1-E8
Continuity mistake: Gambit is the central character in the previous episode "Slave Island", and is on the Blackbird with the rest of the team when they arrive at the destroyed X-Mansion. However, the very next episode begins where "Slave Island" left off, and Gambit is conspicuously missing from the episode.
Continuity mistake: When Magneto destroys the wall of Beast's prison cell, the night sky is visible. When Magneto is asking Beast why he isn't escaping, another wall is now there instead of the sky. (00:03:21 - 00:04:06)
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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