Continuity mistake: When Rogue is checking on Gambit, the black X's on a red background on both of her jacket sleeves are colored entirely red. (00:16:02)
Continuity mistake: When Rogue is flying Gambit back to the mansion, the green sides of her uniform above her belt are incorrectly colored yellow, and Gambit's neck is bare, when it should be colored black because of his headgear. (00:16:14)
Continuity mistake: When Wolverine finds the unconscious Cyclops, Cyclops' sleeve is rolled all the way down. A couple of shots later, the sleeve is now rolled halfway up. (00:16:42)
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 Wolverine returns to Jean and Storm after finding Cyclops, he is standing in the opening of the tunnel. When the shot changes, he is standing near the ladder that was several feet behind him in the previous shot. (00:17:05)
Continuity mistake: When Callisto is saying "Now, for the animal," part of Cyclops' brown pants briefly turn white. (00:17:13)
Continuity mistake: When Wolverine drops Cyclops to the ground, Cyclops' body is at a roughly 45° angle to the tunnel entrance. When Jean intervenes, Cyclops' body is now parallel to the tunnel entrance. (00:17:19)
Continuity mistake: Callisto's staff is roughly the same length as her body. When she is holding the staff to Cyclops' throat, only the bottom quarter of it is visible, when the rest that isn't obscured by their bodies should be visible and pointing outwards at her left. (00:18:06)
Continuity mistake: When Storm and Callisto are about to engage in combat, they are using staves that look like lightsabers, with the hilts at the bottom. When they start striking at each other, both staves now resemble a double-edged lightsaber, with the hilt in the middle. (00:18:25)
Continuity mistake: When Storm is offering the Morlocks sanctuary at the mansion, several of the Morlocks that were standing dozens of feet behind Storm in a previous shot are now standing in front of her. They are then behind Storm again when she is helping Callisto to her feet. (00:18:58 - 00:19:45)
Continuity mistake: When Storm defeats Callisto in combat, Sunder and Tar Baby are in the far background, standing near a tunnel opening. When the shot changes, they are now standing in front of some machinery. (00:18:58)
Continuity mistake: When Xavier is talking to Jean and Cyclops at the end, the three of them, along with Storm, are all to the left of the bed Gambit is lying on, with Storm being behind Xavier, over his right shoulder, and a piece of machinery behind her. When the shot changes, it is a closeup of Xavier, and neither Storm, nor the machinery are visible over Xavier's shoulder. When Jean and Cyclops leave the room, Xavier is now at the foot of Gambit's bed, several feet away from Storm. (00:20:08 - 00:20:32)
Continuity mistake: When Cyclops and Jean Grey enter Wolverine's room at the end of the previous episode and find it a mess and him gone, Cyclops is wearing brown pants, a yellow collared shirt and a charcoal tie, and Jean is wearing a pink dress. This episode picks up where that episode ended, and suddenly Cyclops is wearing blue jeans and a purple turtleneck, and Jean is wearing off-white pants and a turquoise blouse. (00:02:06)
Revealing mistake: When Wolverine is skiing towards the land bridge, his whole body moves back several feet as the camera is panning right. (00:02:54)
Factual error: After Wolverine falls into the ocean, he surfaces and grabs onto a platform of ice just after Sabretooth gloats about defeating him. Since Wolverine's skeleton is coated with a heavy metal, he wouldn't be able to surface. He would sink to the bottom and at the least have to resort walking to the nearby cliff wall and using his claws to scale it until he is back on the ground. (00:03:48 - 00:04:24)
Other mistake: When Gambit, Storm, and Jubilee get into the back of the taxi, you can see the window seat behind the driver is unoccupied, which would suggest the three of them are occupying only two of the backseats. (00:12:51)
Continuity mistake: When Storm, Jubilee, and Gambit are checking into their bungalow, the desk clerk has a rose on his jacket that is missing in a couple of shots. (00:13:10 - 00:13:51)
Continuity mistake: When Storm tells Gambit to put the discount placard back, he sets it in front of the clerk's computer. When the bellhop comes to get everyone's bags, the placard has disappeared. (00:13:24)
Other mistake: When the hotel clerk is checking Gambit, Storm and Jubilee into their room, he determines that they are mutants by seeing footage of Storm using her powers at the Salem Center Mall from the very first episode. While it's not unreasonable that security footage from the mall could exist showing Storm use her powers, the footage also shows an extremely close zoom-in on Storm's left eye, which is extremely unlikely, unless the security camera somehow guessed she was about to activate her mutant powers. (00:13:27)
Continuity mistake: When Wolverine takes the spear out of Kiyoek's hands, it is silver. When he throws it into the water, it is brown. (00:14:36)
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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