Continuity mistake: When Sabertooth is attacking the courtroom, he knocks out three guards with a chair. A couple of shots later, only one guard is on the ground, and when the shot changes again, none of the guards are on the ground anymore. (00:11:15)
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)
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: When Jean removes Cerebro and collapses to her knees, the chair she was sitting in disappears when the shot changes, as does the large roundtable and chairs in the center of the room. Additionally, two red stripes suddenly appear on Cerebro after Jean sets it on the floor. (00:07:42)
Night of the Sentinels: Part 2 - S1-E2
Continuity mistake: When the heroes are shown running away from the Mutant Registration Center, right before the Sentinels show up, Beast is right behind Morph. When Morph gets blasted by the Sentinels, Beast is now nowhere near Morph and shown to be running alongside Gambit and Cyclops. (00:09:51)
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 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 1 - S1-E1
Continuity mistake: When Jubilee blasts Wolverine across the Danger Room, Gambit is shown lying flat on the ground. When the shot changes, he is now resting on his elbows. (00:11:30)
Night of the Sentinels: Part 1 - S1-E1
Continuity mistake: When Jubilee is trying to open the door to the infirmary, the door handle is pointed at roughly 3 o'clock. When she uses her powers to blast the handle off, it is now pointed at roughly 5 o'clock. (00:08:42)
Night of the Sentinels: Part 1 - S1-E1
Factual error: When the Sentinel reaches out to try to grab the dog, it smashes its hand against the grass and produces numerous cracks in the lawn with a metal clanging sound. Neither of these things would happen. The grass would have a bunch of divots in it, and the sound would be similar to something heavy falling in dirt. (00:02:09)
Days of Future Past: Part 2 - S1-E12
Continuity mistake: When Senator Kelly is untying the bound woman, she is in a different part of the room than she was when Kelly and Mystique first entered (note her position relative to the bookshelves). (00:15:50 - 00:16:27)
The Unstoppable Juggernaut - S1-E8
Continuity mistake: When Storm, Rogue and Jubilee are out driving and looking for Wolverine, Rogue's headband is the same color as her flesh. (00:04:45)
Slave Island - S1-E7
Continuity mistake: When Trask is approaching Storm and the other mutants, there is a cliff wall behind him. When the shot changes, it is now the sky behind him. (00:03:55)
Continuity mistake: When Leech steps in front of Cyclops and Jean to steal fruit from the vendor, you can see the street behind him. When the shot changes, there is suddenly what appears to be a covered bus stop behind him. (00:05:48)
Continuity mistake: When Jean and Cyclops are kissing after he tells her his mind is on nothing but her, he is wearing a gray suit jacket, when he was only wearing a yellow collared shirt in all previous shots. (00:05:05 - 00:05:48)
Continuity mistake: When Cyclops and Jean are approaching the newspaper kiosk, its opening is facing the sidewalk. When the shot changes to them walking past it, the opening has been replaced by a wall with newspaper clippings and a painting on it. Moments later, they are approaching the same kiosk, after he tells her that his mind is on nothing but her. (00:05:13)
Continuity mistake: When Wolverine returns to Storm and Jean, you can see no-one is in his immediate vicinity. A couple of shots later, Callisto and Annalee are standing by the tunnel entrance, a few feet to Wolverine's left. (00:17:05)
Continuity mistake: When Leech begins to telekinetically steal fruit from the vendor cart, he is stealing a red apple and what appears to be an orange with a yellow peel. When the shot changes, the orange is now orange in color, and as the two pieces of fruit move towards Leech, the orange is on his right, and the apple on his left. When the shot changes, the orange is now yellow in color again, and the fruits have swapped sides. (00:05:52)
Continuity mistake: When Wolverine says to Sabretooth "Be careful what you ask for," his arms are yellow. (00:17:05)
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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