Dark Phoenix (1): Dazzled - S3-E11
Other mistake: The episode begins with an out-of-place one-second shot of a door opening on a space craft revealing a satellite hovering over Earth before quickly cutting to an establishing shot of Muir Island. Note: this may only apply to the version of the episode that appears on Disney+. (00:01:00)
The Dark Phoenix (4): The Fate of the Phoenix - S3-E14
Continuity mistake: When Gambit and Storm were knocked unconscious in battle, they were lying next to each other. When Xavier revives them in order to stop Dark Phoenix, they are several feet away from each other. (00:10:54 - 00:15:15)
Dark Phoenix (1): Dazzled - S3-E11
Audio problem: When the White Queen says "She's asleep," her mouth is closed for the first word. (00:12:39)
The Dark Phoenix (4): The Fate of the Phoenix - S3-E14
Continuity mistake: When Earthquake knocks out Gambit and Storm, he and Hussar are offscreen to the viewer's left. When the shot changes, Hussar is standing directly behind where Gambit and Storm's heads are pointing. (00:10:54)
The Dark Phoenix (4): The Fate of the Phoenix - S3-E14
Revealing mistake: When Oracle attacks Jean, a beam of psychic energy emanates from Oracle's body. The beam then remains in place as Oracle moves towards Jean, likely indicating a composite shot. The beam is then back in place when the shot changes. (00:09:55)
The Dark Phoenix (4): The Fate of the Phoenix - S3-E14
Continuity mistake: When the X-Men are standing on the platform waiting to be transported to the Moon, Gambit is standing directly behind Jean and Cyclops, with Storm on his right. When the shot changes, Gambit has disappeared. (00:08:34)
The Dark Phoenix (3): The Dark Phoenix - S3-E13
Continuity mistake: When Jean collapses after the psychic battle between Xavier and Dark Phoenix, she falls onto the grass. When the shot changes, she is lying on the street. (00:18:33)
The Dark Phoenix (3): The Dark Phoenix - S3-E13
Continuity mistake: When Xavier first confronts Dark Phoenix inside Jean's mind, the flaps of Dark Phoenix's waistband are pointed outwards. When the shot changes, they are pointing down. (00:17:15)
The Dark Phoenix (3): The Dark Phoenix - S3-E13
Continuity mistake: When Dark Phoenix recovers from Xavier's psychic attack, Storm, Wolverine and Gambit are standing next to her. When the shot changes, Wolverine and Storm have swapped places. Additionally, Gambit's sclera are white when they should be black. (00:16:44)
The Dark Phoenix (3): The Dark Phoenix - S3-E13
Continuity mistake: When Dark Phoenix traps the X-Men in an energy field, their orientation within it varies throughout the scene. (00:15:45 - 00:16:27)
The Dark Phoenix (3): The Dark Phoenix - S3-E13
Continuity mistake: When Jean is giving Wolverine permission to kill her, Wolverine's bare arms have been colored yellow. (00:15:09)
The Dark Phoenix (3): The Dark Phoenix - S3-E13
Continuity mistake: When Cyclops is telling Jean that they all love her and that she loves all of them, Storm has disappeared from the wall of energy that the rest of the X-Men are trapped in. (00:16:10)
The Dark Phoenix (3): The Dark Phoenix - S3-E13
Revealing mistake: After Wolverine tackles Jean, the glowing effect of the mnemonic scrambler device on her head briefly moves to a different part of her head. (00:15:08)
The Dark Phoenix (3): The Dark Phoenix - S3-E13
Continuity mistake: When Jean runs out of her childhood home to greet who she thinks is her father, there is a short picket fence lining the front yard that wasn't there in the establishing shot of the house. The yard itself also appears to have shrunk. (00:12:58 - 00:14:24)
The Dark Phoenix (3): The Dark Phoenix - S3-E13
Continuity mistake: When Jean Grey returns to her childhood home, the panels on the front door as she walks in are shorter than they were in the establishing shot. The door also changes from green to brown. (00:12:58)
The Dark Phoenix (3): The Dark Phoenix - S3-E13
Continuity mistake: When the X-Men are first shown in the dining hall, Gambit and Rogue have empty hands, and Gambit is also wearing gloves. When the shot changes, both are now gripping coffee mugs, and Gambit is barehanded. (00:10:06)
The Dark Phoenix (3): The Dark Phoenix - S3-E13
Continuity mistake: When Harry Leland and Sebastian Shaw are watching the Dark Phoenix battle the X-Men from afar, the "tiger stripes" that were on their vests in the two previous episodes are missing. (00:06:52)
The Dark Phoenix (3): The Dark Phoenix - S3-E13
Continuity mistake: When Dark Phoenix knocks out Cyclops, his visor flies off his face and lands on the ground several inches from his outstretched left arm. When the shot changes, the visor is suddenly pressed up against his arm. (00:06:28)
The Dark Phoenix (3): The Dark Phoenix - S3-E13
Continuity mistake: When Wolverine is walking out of the pond, he can be seen wiping a red substance off his left shoulder that wasn't there in previous shots. (00:03:51)
The Dark Phoenix (2): The Inner Circle - S3-E12
Continuity mistake: When Beast jumps down to attack Sebastian Shaw, his waistband changes from red to yellow. (00:17:07)
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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