Continuity mistake: After Moira and Banshee are knocked back into the wall by Proteus, the amount of rubble around them changes between shots. (00:02:15)
Continuity mistake: During Xavier's flashback, Jean Grey goes from wearing her current (as of the show's broadcast) uniform while training in the Danger Room to her original "Marvel Girl" uniform when Amelia is leaving the mansion. Additionally, when Xavier is talking to Amelia in the Danger Room's control room, he is in his usual hoverchair, yet when Amelia is leaving the mansion, he is in a regular wheelchair. (00:05:25)
Deliberate mistake: The security footage of Proteus' escape from the Muir Island Research Facility is merely the same earlier scene played over again. (00:06:50)
Continuity mistake: When Wolverine, Rogue and Beast are approaching Proteus in the Blackbird, in the first shot you can see through the windows that Wolverine is wearing a jacket. When the shot changes, the jacket is suddenly gone. (00:13:05)
Revealing mistake: When Moira gets up from her seat to check on Xavier, her left leg passes through the left armrest. (00:14:45)
Continuity mistake: When Proteus possesses the truck driver, the truck driver's wristwatch disappears in one shot. (00:15:10)
Factual error: When Moira is calling her ex-husband Joe in Edinburgh from the Blackbird phone, she dials a typical U.S. seven-digit phone number (it looks like she dials 555-1238). However, even assuming she wouldn't be required to dial an exit code from the Blackbird, a typical Edinburgh phone number would have more digits, along the lines of +44-131-XXX-XXXX. (00:16:50)
Continuity mistake: After Joe hangs up on Moira, if you look at Wolverine in the background you will see that his face is colored yellow. (00:17:30)
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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