Night of the Sentinels: Part 2 - S1-E2
Continuity mistake: When Gyrich is telling Jubilee that he wants to ask her about the mutants that helped her at the mall, the microphone is up to his mouth. When the shot changes to him tapping his right index finger on the desk, the microphone is nowhere near his mouth. (00:04:27)
Night of the Sentinels: Part 2 - S1-E2
Continuity mistake: When Storm is saying "We must destroy every registration file in this area," Beast is standing behind her. When the shot changes, he is standing in front of her. Additionally, Beast's black eyebrows are incorrectly colored blue in one shot. (00:03:51)
Night of the Sentinels: Part 2 - S1-E2
Continuity mistake: At the beginning of the scene where Morph is impersonating a commanding officer, a guard is shown with a golden-brown colored name tag that turns green as he moves towards the camera, and the writing disappears. (00:03:29)
Night of the Sentinels: Part 1 - S1-E1
Continuity mistake: When Gambit is saying he could easily break into the Mutant Registration Center by himself, Morph is wearing yellow gloves. When Morph suggests going into the building disguised as Gambit, his hands are suddenly bare. (00:15:45)
Night of the Sentinels: Part 1 - S1-E1
Continuity mistake: When Jubilee is saying "That's a nice way of saying 'mutants'," the black horizontal line on her left earring briefly turns the same red color as the rest of the earring. (00:12:59)
Night of the Sentinels: Part 1 - S1-E1
Continuity mistake: When Gambit and Wolverine are sparring in the Danger Room, at one point Gambit dives onto a piston and then rolls off moments before it smashes him into another piston, with a piece of the bottom right of his trenchcoat being torn off in the process. When Jubilee is explaining to everyone that she was trying to help Gambit, his trenchcoat is now untorn. (00:11:07 - 00:11:43)
Night of the Sentinels: Part 1 - S1-E1
Continuity mistake: When Gambit lands in the car, his trenchcoat is entirely within the car. When the Sentinel is shown approaching the car, the bottom of the trenchcoat is now hanging over the passenger side door. (00:07:11)
Night of the Sentinels: Part 1 - S1-E1
Continuity mistake: Just before Jubilee accidentally destroys the arcade game she is playing, you can see a basket of chili fries resting on the game's control panel, and the chili is a dark green color. When the shot changes, the chili is now reddish-brown. (00:03:23)
Night of the Sentinels: Part 1 - S1-E1
Continuity mistake: When the dog is barking at the Sentinel, the sidewalk is crumpled from the Sentinel landing on it. When the Sentinel reaches out for the dog, the sidewalk is now undamaged. (00:02:06)
Slave Island - S1-E7
Continuity mistake: When Gambit is preparing to blow the door off Storm's solitary lockbox, his black sclera are briefly incorrectly colored white. (00:13:37)
Night of the Sentinels: Part 2 - S1-E2
Continuity mistake: When Storm is flying away with Cyclops in tow, she is holding him by his left arm. A couple of shots later, she is holding him by his right arm. (00:11:25)
Continuity mistake: When Jubilee raises Sabretooth's arm restraint, the interior side of it is shown to extend all the way down to the arm rest. When the shot changes, it now has an opening for a person to move their arm through. (00:15:31)
Continuity mistake: When Sabretooth is trying to force Wolverine's claws into his own face, they are next to a set of steps. When the shot changes, there are no steps anywhere near them. (00:18:46)
Continuity mistake: When Sabretooth is trying to force Wolverine's claws into his own face, the black part of Wolverine's mask on either cheek is incorrectly colored yellow. (00:18:13)
Continuity mistake: Numerous episodes depict the War Room as being a circular room completely enclosed from the rest of the underground facilities. However, when Wolverine is confronting Sabretooth in the War Room, it is a wide open area with numerous corridors. (00:16:23 - 00:17:05)
Continuity mistake: When Sabretooth is watching Senator Kelly's press conference, his chair is directly facing the TV. After Jubilee turns off the TV and walks towards Sabretooth, his chair has now rotated roughly 90° clockwise. (00:14:47)
Continuity mistake: When Senator Kelly is giving a press conference to declare his candidacy for President, at the start there is a flag immediately to his right. When the shot changes, after a few seconds the camera pans out and the flag has now moved several more feet to his right. (00:14:05)
Continuity mistake: When Rogue is blindly searching for Cyclops, the black circle with the red X on her chest is now a red circle with a yellow X. (00:11:14)
Continuity mistake: When Storm is free-falling after stopping the missiles, the communication device on her left side is flashing as Cyclops is speaking to her, and as her body rotates, it becomes the right side device that flashes. (00:19:53)
Continuity mistake: When the people begin throwing tomatoes at Beast, the judge in the background is sitting down. When the shot changes, he is standing. (00:10:04)
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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