Revealing mistake: In the opening shot of the Washington Monument, the monument is very noticeably shaking left and right as the camera pans up (likely indicating that the monument and the background are a composite image). (00:01:00)
No Mutant Is an Island - S5-E4
Revealing mistake: When Killgrave is saying "On your knees," his eyes jump off his face. (00:18:45)
No Mutant Is an Island - S5-E4
Revealing mistake: When Rusty is being brainwashed, his eyes move down his cheeks as his head nods. (00:10:55)
No Mutant Is an Island - S5-E4
Revealing mistake: When Sarah turns off the stove burner you can see that there is an outline of a knob that the animators either forgot to fill in or forgot to erase. (00:05:35)
Revealing mistake: When Rogue is shown tearing off the first portion of the submarine's hull, her feet are missing. (00:17:55)
The Phalanx Covenant: Part 2 - S5-E2
Revealing mistake: When Forge says "That's where we'll begin our assault," his mustache disappears from his face. (00:14:50)
The Phalanx Covenant: Part 2 - S5-E2
Revealing mistake: The shot of Cameron Hodge glaring at Xavier after Xavier asks him about his lack of humanity is a recycled shot from the previous episode. (00:14:30)
The Phalanx Covenant: Part 1 - S5-E1
Revealing mistake: When Beast lunges away from the Phalanx disguised as several people in hazmat suits, after he lands he glides across the grass. (00:08:15)
The Phalanx Covenant: Part 1 - S5-E1
Revealing mistake: The shot of police cars surrounding Sabretooth and him throwing one of them into the air is a recycled shot of the very first shot in the series from the season 1 episode "Night of the Sentinels, Part 1." It's even revealed a few minutes later in the episode that this isn't actually Sabretooth, but a Phalanx facsimile that has taken his form, which makes the fact that Sabretooth's actions are being recycled all the more dubious. (00:01:35)