Beyond Good and Evil: Part 4 - S4-E11
Continuity mistake: The end of the episode shows Xavier standing with no assistance. The only time in the series that the use of his legs were restored were a side effect of him losing his powers. He has his powers in this scene, so there's not really any reason for him to suddenly have the use of his legs back. (00:19:15)
Beyond Good and Evil: Part 3 - S4-E10
Continuity mistake: When the Four Horsemen are retreating back into the pyramid, the opening is shown to be illuminated. When they are shown entering the opening, it is in darkness. (00:17:15)
Beyond Good and Evil: Part 2 - S4-E9
Continuity mistake: Magneto straps Wolverine to the port side of a boat and then drops the boat on a warehouse. When Gambit is freeing Wolverine, Wolverine is suddenly on the starboard side of the boat. After Gambit frees Wolverine, they are both shown to be on the boat's port side. (00:17:00 - 00:18:00)
One Man's Worth: Part 1 - S4-E1
Continuity mistake: When the coffee shop owner is strong-arming Xavier, he is first shown gripping Xavier by the collar of his sweater. A couple of shots later, the coffee shop owner's hand is gripping the collar from inside the sweater. (00:15:30)
Family Ties - S4-E17
Continuity mistake: When Wolverine is talking to Xavier by the fireplace, in one shot the black portion of his mask is colored yellow. (00:05:20)
Family Ties - S4-E17
Continuity mistake: There are two continuity errors regarding the final shot of Wolverine in this episode. Firstly, his arms are colored yellow. Secondly, his costume has magically mended itself after being torn to shreds by his mutation earlier in the episode. (00:20:25)
Family Ties - S4-E17
Continuity mistake: When Wolverine is mutated into a werewolf-like monster, portions of his costume are torn up including his boots. When he reverts back into human form, his boots are still torn up, but his bare feet are still colored blue. (00:19:10)
Family Ties - S4-E17
Continuity mistake: When the mutated Wolverine picks up and throws Xavier, before Beast comes to aid him there is nothing immediately around Xavier but the ground. When the shot changes, Xavier and Beast are suddenly next to a cliff wall. (00:17:55)
Family Ties - S4-E17
Continuity mistake: When Magneto rescues Beast, the purple border at the base of his helmet is suddenly red. (00:17:15)
Family Ties - S4-E17
Continuity mistake: When the High Evolutionary is talking about using the speed enhancing powers of Quicksilver's DNA, the lightning bolt symbol is missing from Quicksilver's uniform. (00:13:40)
Family Ties - S4-E17
Continuity mistake: At various points in the episode, the High Evolutionary's "teeth" go from being white to being the same purple color as his face. (00:05:45 - 00:13:40)
Family Ties - S4-E17
Continuity mistake: When Magneto is explaining the legend of Wundagore to Wolverine, Quicksilver and Scarlet Witch are just a few feet behind him. When the High Evolutionary greets Magneto, Quicksilver and Scarlet Witch have suddenly moved several yards away. (00:12:50)
Family Ties - S4-E17
Continuity mistake: After Magneto and Wolverine have been captured, when Wolverine is asking Magneto what is going on, the perspective of the shot makes it look like Magneto is looking down on Wolverine from a considerably taller height when they are both standing on a level floor. Additionally, the square slabs that make up the floor become smaller. (00:12:35)
Family Ties - S4-E17
Continuity mistake: For the first half of this episode, Magneto is wearing a red dress-shirt with a black tie under a dark gray trenchcoat. After he is captured by the High Evolutionary, he is suddenly wearing his usual red and purple costume. Even if Magneto brought a change of clothes with him, it's extremely unlikely that the High Evolutionary would change his clothes for him. (00:03:40 - 00:12:40)
Family Ties - S4-E17
Continuity mistake: The metal tubes on Wolverine's gloves appear and disappear throughout the episode. (00:04:00 - 00:20:45)
Family Ties - S4-E17
Continuity mistake: The style of the lettering on Magda's gravestone changes after the goat-woman runs away from Magneto. There is also a stone that was next to the grave when it is first shown that has suddenly disappeared in the same shot of the goat-woman running away. (00:09:10 - 00:09:45)
Family Ties - S4-E17
Continuity mistake: Quicksilver's neck is colored the same light-blue hue as his uniform when he says "The mutant who did this..." (00:07:45)
Family Ties - S4-E17
Continuity mistake: When Scarlet Witch and Quicksilver first meet the High Evolutionary, Scarlet Witch's headgear alternates between being red and pink. (00:05:55)
Family Ties - S4-E17
Continuity mistake: When Bova is bringing the baby twins to Django and Marya's house, the arm she is carrying the respective twin in changes depending on the shot. When she is first shown walking towards the house, she is holding Wanda in her left arm and Pietro in her right. When she is walking up the steps to the door, she is carrying Pietro in her left arm and Wanda in her right. When the shot changes after Django opens the door, the twins have switched arms again, and then again when she hands the babies to Django and Marya. (00:02:30)
Continuity mistake: When Xavier is explaining to Wolverine the importance of vigilance, Beast can be seen directly behind him. When the shot changes, Beast is no longer standing behind Xavier. (00:18:25)
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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