Slave Island - S1-E7
Continuity mistake: Before the mutants ambush the guards, they are walking in a single-file line, with Sunfire in front, followed by Jubilee, Mystique, Caliban, an unnamed female mutant, and Aurora. A couple of shots later, either Aurora or her similarly-dressed twin brother Northstar is suddenly at the front of the line. (00:08:55)
Slave Island - S1-E7
Continuity mistake: When the Sentinel puts Jubilee in the detention box, it is still dark outside. A couple of shots later and there is a considerable amount of daylight in the sky. (00:09:30)
Slave Island - S1-E7
Continuity mistake: When Gambit is being escorted into the Sentinel factory, he has two guards behind him on his right and left. When the shot changes, the guards have disappeared. (00:11:00)
Slave Island - S1-E7
Continuity mistake: After Gambit jumps out of the moving hovercar, it comes to a stop in the middle of the road. When the shot changes, the hovercar is suddenly on the left side of the road (note the yellow lane dividers), and is no longer casting a shadow. (00:12:00)
Slave Island - S1-E7
Continuity mistake: When Gambit tries to grab the gun, Cable stops him by placing his left foot on top of it. When the shot changes, it is now Cable's right foot that is on the gun. Additionally, yellow lane dividers in the middle of the road disappear when Gambit first reaches for the gun, and then reappear a couple of shots later. (00:12:15)
Slave Island - S1-E7
Continuity mistake: After Gambit unlocks his collar, he lets the collar fall to the ground. In the next shot, the collar is visible on the ground a couple feet in front of him. In the shot after that when he retrieves the gun, the collar is no longer visible on the ground. (00:12:50)
Slave Island - S1-E7
Continuity mistake: When Cameron Hodge is telling Gyrich and Trask about Cable, the books on the table move closer to Hodge between shots. (00:13:10)
Slave Island - S1-E7
Continuity mistake: When Gambit is preparing to blow the door off Storm's solitary lockbox, his black sclera are briefly incorrectly colored white. (00:13:37)
Slave Island - S1-E7
Continuity mistake: When Gambit is carrying Jubilee over his shoulder, the placement of his hand alternates between being on the small of her back, the back of her thighs, or her butt depending on the shot. (00:13:55)
Slave Island - S1-E7
Continuity mistake: When Cable shoots his exploding plasma blast at the conference table, the blast is shown coming through the window from a downward angle. However, the tree branch that Cable is subsequently shown to be using as his vantage point is lower than the window, so the blast could not have come at a downward angle. (00:14:45)
Slave Island - S1-E7
Continuity mistake: When the Genosha guard tries pulling a gun on Cable, you can see his headgear only extends down to his jawline and chin. When Cable picks him up and throws him, his headgear is now also covering his entire neck. (00:19:00)
Slave Island - S1-E7
Continuity mistake: When Cyclops is trying to radio Professor X from the Blackbird, there is a window immediately to Cyclops' right. When the shot changes, Jean Grey is suddenly seated on Cyclops' right. (00:20:00)
Slave Island - S1-E7
Continuity mistake: When Storm is asleep, her lightning bolt earrings appear to be connected through the back of her earlobes. When she wakes up, the earrings are now on the front of her earlobes. (00:20:15)
Slave Island - S1-E7
Continuity mistake: The keyhole on Gambit's inhibitor collar alternates between being mostly the same yellow color as the rest of the collar, and being gray such as when he unlocks it.
Slave Island - S1-E7
Continuity mistake: Throughout the episode, the inhibitor collars worn by the captured mutants alternate between having a leveled edge like a hardware nut, to having a rounded edge like a finger ring.
The Unstoppable Juggernaut - S1-E8
Continuity mistake: At the beginning of the episode when the camera zooms into the Blackbird through its front windows, you can see Wolverine is sitting directly behind Cyclops, and Rogue is seated on Wolverine's left. A few shots later, Wolverine is now sitting where Rogue was seated. (00:02:04)
The Unstoppable Juggernaut - S1-E8
Continuity mistake: When the team arrives at the destroyed mansion at the end of the previous episode, Cyclops' seat is blue, Rogue says "It can't be" while raising her right hand up to her mouth in disbelief, and Wolverine is growling and extending his claws. When the team is shown arriving at the destroyed mansion at the beginning of this episode, Cyclops' seat is now light-red, Rogue says "It can't be" while her arms remain at her sides, and a silent Wolverine is casually putting on his mask and walking towards the exit ramp of the Blackbird. (00:02:23)
The Unstoppable Juggernaut - S1-E8
Continuity mistake: When Jean Grey is saying "What if the professor's in there," her hand is colored blue, when it should be flesh-colored. (00:02:36)
The Unstoppable Juggernaut - S1-E8
Continuity mistake: When Jubilee is bringing up the message from Xavier, her head is below the top of her chair's headrest. When the shot changes, her head is higher than the headrest. (00:03:41)
The Unstoppable Juggernaut - S1-E8
Continuity mistake: When Xavier's message begins playing, Jubilee is sitting down, and Storm and Rogue are standing side by side. When the shot changes, Jubilee is standing up, and Storm is now in front of Rogue. (00:03:46)
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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