Continuity mistake: When they first run away from the Spirit Drinker, Wolverine is kneeling down and cradling the unconscious Jubilee, with Gambit behind Wolverine, and Lady Deathstrike on Wolverine's left. When the shot changes, you can tell by the brown boots that Lady Deathstrike is now standing behind Wolverine instead of Gambit. (00:04:50)
Continuity mistake: When Gambit is saying "How are we gonna beat this thing when we can't even get close to it?", Jean Grey is on the viewer's left of the group and Cyclops is on her left. When the shot changes, Jean and Cyclops have swapped places. (00:16:31)
Continuity mistake: When Gambit is saying "Now what do we do?" after throwing a kinetically charged card at the Spirit Drinker, the glove on his left hand is suddenly missing. (00:07:54)
Continuity mistake: When Jubilee is saying "But the others," she is standing directly in front of Gambit. When the shot changes, she is no longer in front of Gambit. When the shot changes again, she is suddenly behind Gambit. (00:03:57)
Continuity mistake: When Beast and Xavier first enter the alien craft, Beast's black eyebrows are incorrectly colored blue for a couple of shots. (00:13:58)
Continuity mistake: When Jean tries to probe the Spirit Drinker's mind, she is standing several feet from the wall on her left. When Cyclops checks to see if she's all right, she is suddenly much closer to the wall. (00:12:07)
Continuity mistake: When Beast begins leaving the art museum, the painting behind him is a Picasso. When the shot changes, it is a different painting. (00:05:49)
Continuity mistake: Wolverine's 5 o'clock shadow disappears and reappears throughout the episode.
Continuity mistake: Beast is present when Gambit destroys the Spirit Drinker. When Professor X arrives moments later, Beast is shown to be approaching the scene with him and then notes that the Spirit Drinker seems to be missing. (00:18:45 - 00:19:25)
Continuity mistake: Gambit is missing his gloves when Jean Grey stops him, Wolverine and Cyclops to tell them what Professor X told her about the alien ship. (00:15:20)
Continuity mistake: The warning sign on the containment vessel inside the alien ship disappears in the wide shot. (00:14:40)
Continuity mistake: Gambit's black cowl is suddenly blue when Jean Grey is explaining that the alien spacecraft is a prison ship. (00:15:25)
Continuity mistake: When Wolverine says "Come on kid" to the unconscious Jubilee, the fingers of his left hand are flesh colored when they should be colored blue from wearing gloves. (00:04:50)
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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