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)
Continuity mistake: When Wolverine and Cyclops are first shown sitting in the courtroom gallery, the wall behind them is bare. When the shot changes, a door has appeared behind them. (00:08:25)
Night of the Sentinels: Part 2 - S1-E2
Continuity mistake: When Jubilee is saying goodbye to her foster parents, the topper on the roof of the taxi has "Taxi" written in bold lettering. When Jubilee is getting in the taxi, the lettering is nowhere near as bold, and an extra light has appeared on each side of the taxi, under the headlights. (00:20:01)
Night of the Sentinels: Part 2 - S1-E2
Continuity mistake: When Storm destroys the final Sentinel, Gambit and Jubilee walk right up to it, and there are no other Sentinels near it. When the shot changes, there is another Sentinel on the ground right behind Gambit and Jubilee. (00:19:56)
Night of the Sentinels: Part 2 - S1-E2
Continuity mistake: When the Sentinel is firing at Storm inside the factory, two of its blasts are emanating from the wrong side of its hand. (00:19:00)
Night of the Sentinels: Part 2 - S1-E2
Continuity mistake: When Cyclops blasts off the Sentinel's arm, part of its shoulder is still intact. When it begins flying back to base for repairs, the entire arm is now missing. (00:16:18)
Night of the Sentinels: Part 2 - S1-E2
Continuity mistake: When the President is using the elliptical machine, she has an aide standing to her left. A couple of shots later, the aide is now standing behind the President. (00:14:56)
Night of the Sentinels: Part 2 - S1-E2
Continuity mistake: When the President is first shown on TV, the Great Seal behind her looks more like a shield before being shown to be an eagle a few shots later. (00:13:11)
Night of the Sentinels: Part 2 - S1-E2
Continuity mistake: When Cyclops is standing in the doorway to the garage, the communication device on his bandolier is entirely red, when there should be a black X on it as well. (00:09:42)
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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