
Slave Island - S1-E7
Plot hole: After Storm's attempt to escape the Genoshan prison is thwarted, she ends up in the ocean right at the shoreline of the beach, where she is captured by a Sentinel. Aside from the fact that it makes no sense for a Sentinel to be hiding in the ocean in the event that a mutant tries to escape the prison, there is absolutely no way that a two-story tall robot could hide in the ocean right by the beach, as the water would be way too shallow. You can even see that the water level only goes up to the Sentinel's ankle area when it is standing upright in the ocean. (00:03:15)

The Dark Phoenix (2): The Inner Circle - S3-E12
Continuity mistake: Rogue rips off Donald Pierce's cybernetic left arm, but when he is first shown running away, his right arm is the one that is missing. When he catches up with Sebastian Shaw in the secret passageway, his left arm is back to being the one missing. (00:18:30)

Continuity mistake: Wolverine first enters the sewers by ripping away a fence in the subway. When Jubilee and Gambit follow him, the fence is still intact. When they get closer it is torn again. Odd, really, because on the whole this show has few continuity errors, like self-mending clothes in other cartoons.

Time Fugitives: Part 1 - S2-E7
Factual error: Costumed superheroes notwithstanding, Bishop wouldn't be allowed to bring his gun into the United States Capitol. (00:14:40 - 00:16:10)

Days of Future Past: Part 2 - S1-E12
Revealing mistake: When Gambit draws a card from his sleeve to use as a trap, the gloved part of his hand that is below the pocket is translucent. (00:09:28)

Continuity mistake: When Storm is watching TV with her arms folded, her left hand shows her index and middle fingers touching. When the shot changes, it is her middle and ring fingers that are touching. (00:08:40)

Continuity mistake: When Archangel is lamenting his actions, the communicator devices from Storm's uniform are missing. (00:20:15)

Continuity mistake: When the three horsemen are climbing onto their mechanical horses, Famine's horse is in the middle, and Pestilence's horse is on the right. Once all three have all been individually shown to be mounting their horses, Famine and Pestilence have swapped places. (00:06:08)

Continuity mistake: When Gambit is saying "Someone may be tracking us," the snaps on both shoulders of his jacket are colored blue, when they should be the same brown color as the rest of his jacket. (00:11:45)

Trivia: One of the images in Gambit's mind-scan is of fellow Marvel Comics superhero Ghost Rider. (00:07:45)

Revealing mistake: When Rogue puts the dome in place, if you look closely you will see that the dome is resting on thin air (note that you can see the sky through the platform she sets it on, and when she sets it down, the underside of the dome is visible). (00:06:15)

One Man's Worth: Part 1 - S4-E1
Character mistake: When the civilians are fleeing the coffee shop, there are two spelling errors on the coffee shop's marquee. Firstly, the name of the coffee shop is Rip Van Winkle, but on the marquee, Winkle is spelled as "Winkile." To the right of that, Coffee House is spelled as "Coffe House." (00:16:55)

One Man's Worth: Part 1 - S4-E1
Trivia: The man that aids Wolverine in the coffee shop is Johnny Strabler, Marlon Brando's character from the film "The Wild One." (00:16:45)

Have Yourself a Morlock Little Christmas - S4-E12
Other mistake: When Gambit is tasting the food in the crock pot, his left arm has been drawn backwards.

Continuity mistake: When Gambit first walks into Bobby's cell, Bobby is sitting in a chair up against the back wall. A few shots later, Bobby is sitting in the center of the cell. (00:09:55)

Continuity mistake: Bella Donna's engagement/wedding ring from Gambit doesn't appear on her finger until she mentions that she still wears it. (00:10:55)

Family Ties - S4-E17
Revealing mistake: When Quicksilver is fidgeting inside his containment shell, the animators neglected to properly sync his body movement. You can see that his shoulders are not "connected" to his arms, as if his head and shoulders were separated from the rest of his body. (00:16:00)

Secrets, Not Long Buried - S4-E15
Revealing mistake: When the Lady Gardener shuts her door on Cyclops, his right arm stays inside her house in front of the door frame. (00:14:35)

Secrets, Not Long Buried - S4-E15
Revealing mistake: Instead of staying in place, the energy surging around Watchdog's head moves down the screen as the camera pans down. (00:02:35)
Chosen answer: It says MPO "First Exemplary Printing House" which is a real printing company in Russia founded by Ivan Dmitrievich Sytin in 1889. There seems to be something about "named after..." as well.
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