The One With the Sharks - S9-E4
Revealing mistake: While Monica and Rachel are talking about Chandler's "jollies to Jaws" Rachel's wearing a colorful flowery top, and after Joey walks in just as Monica takes her seat at the table in the closeup, it's Jennifer Aniston's stand-in, wearing a blue top, who is seated beside Monica. Rachel's hair is wavy in the flowered top, but straight in the blue top (viewed in widescreen). (00:12:22)
Visible crew/equipment: When the son of the accident victims is being led through the trauma rooms to see his parents' bodies, you can see Laura Innes crouching under a table in the background directing the scene. Innes was the director of this episode and it was established that this episode took place on her character's day off. Therefore, she should not have appeared in front of the camera at all. (00:32:30)
Sins of the Fathers Chapter 3: Attack of the Octobot - S3-E3
Factual error: When Spider-Man and Doc Ock are talking in the lab, at one point, a shot of Doc Ock's face shows Spider-Man reflected in each side of his sunglasses. However, Doc Ock's glasses have a singular lens, and the straight angle of Spider-Man's reflections suggest that the glasses are in no way curved, so Spider-Man should only be reflected in them once.
Silence My Companion, My Death Destination - S1-E4
Continuity mistake: When Julia is first seen monitoring Iron Man's space mission, the bracelet she is wearing on her left wrist throughout the scene is not there. (00:04:07)
The Silver Surfer & the Coming of Galactus: Part 1 - S1-E5
Continuity mistake: When Thing is asking if 600°F is hot after Reed helps Sue get into the Fantasticar, Reed's hair is blonde when it should be brown. (00:05:34)