Have Yourself a Morlock Little Christmas - S4-E12
Other mistake: Jubilee should not have been able to see Mariana without looking around the corner. (00:10:25)
Have Yourself a Morlock Little Christmas - S4-E12
Continuity mistake: Callisto's eye-patch changes sides when she is berating Storm. (00:09:30)
Have Yourself a Morlock Little Christmas - S4-E12
Continuity mistake: Jubilee's presents suddenly become smaller when she, Storm and Wolverine depart for the Morlock tunnels. (00:08:45)
Have Yourself a Morlock Little Christmas - S4-E12
Other mistake: When Ape and Annalee walk to the back doors of the ambulance, the window on the right rolls down. Ignoring the fact that those windows don't actually roll down, neither Ape nor Annalee do anything to make it roll down. (00:06:55)
Have Yourself a Morlock Little Christmas - S4-E12
Continuity mistake: The boxes and ribbons in the stack of gifts that Jubilee is carrying change color. (00:05:20)
Beyond Good and Evil: Part 4 - S4-E11
Audio problem: After Bender reverts to his true form of Immortus, he laughs before disappearing. The laugh is oddly inaudible on the DVD. (00:18:50)
Beyond Good and Evil: Part 4 - S4-E11
Continuity mistake: The same time portal with the image of the neanderthal by the fire is erased by Apocalypse twice. (00:12:45)
Beyond Good and Evil: Part 4 - S4-E11
Other mistake: During the montage of people being erased from time, the exterior shot of the X-Mansion shows part of the mansion destroyed. The mansion is later shown to be destroyed by Graymalkin after the heroes defeat Apocalypse, but at this point in the episode there's no reason for the damage. (00:12:20)
Beyond Good and Evil: Part 4 - S4-E11
Revealing mistake: After the horsemen collect the orb from Apocalypse, a second "onion skin" head of Apocalypse appears. (00:11:45)
Beyond Good and Evil: Part 4 - S4-E11
Continuity mistake: When Mr. Sinister confronts Magneto and Mystique, he is by himself. In the next shot, the Nasty Boys are suddenly behind him. (00:09:15)
Beyond Good and Evil: Part 4 - S4-E11
Continuity mistake: When the X-Men are fleeing the pyramid, Gambit's normally-black pants are colored blue. (00:03:20)
Beyond Good and Evil: Part 3 - S4-E10
Continuity mistake: At the end when Mystique says "What was that?" her normally-red eyebrows are colored white. (00:19:40)
Beyond Good and Evil: Part 3 - S4-E10
Continuity mistake: When Wolverine sniffs out one of Apocalypse's booby traps, the portion of his mask that runs down either side of his cheeks that is normally colored black is now colored yellow. (00:16:30)
Beyond Good and Evil: Part 3 - S4-E10
Continuity mistake: When Beast opens up the entrance to Apocalypse's pyramid, the "X" symbol on his belt that is normally black on red is now red on yellow. (00:15:15)
Beyond Good and Evil: Part 3 - S4-E10
Continuity mistake: When Beast is asking Xavier what he saw in Sabretooth's mind, Beast is missing the "X" symbol from the center of his belt. (00:11:10)
Beyond Good and Evil: Part 3 - S4-E10
Continuity mistake: When Cable is ordering Xavier to probe Sabretooth's mind, Cable is carrying his gun in his right hand. When the shot changes, Cable is no longer holding his gun. (00:10:55)
Beyond Good and Evil: Part 3 - S4-E10
Continuity mistake: When Cable is ordering Xavier to probe Sabretooth's mind, Sabretooth's normally-brown headgear is flesh-colored. (00:10:50)
Beyond Good and Evil: Part 3 - S4-E10
Continuity mistake: When Cyclops and Cable are arguing about the course of action to take, Cyclops is on the viewer's left and Cable on the right. When Wolverine interrupts them, they have swapped sides. (00:10:25)
Beyond Good and Evil: Part 3 - S4-E10
Continuity mistake: When Cable says "You're boring me..." to Xavier, Cable's gun is missing. It reappears in the next shot. (00:08:20)
Beyond Good and Evil: Part 3 - S4-E10
Continuity mistake: The position of Cable's gun when it is holstered on his back varies throughout the episode. Sometimes it is slanted at a 45° angle with the butt going over his right shoulder, sometimes it is sticking straight up with the butt going over his left shoulder, etc.
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.
BaconIsMyBFF