Visible crew/equipment: When Kel gets up to get more water you can see one of the cameras.
Continuity mistake: Ray places a donut that Debra throws at him on the third step and then stands up. Later the donut appears on the second step when Frank comes down the stairs. (00:19:15 - 00:20:45)
Not in the Line of Fire - S3-E15
Continuity mistake: When the vendor throws the hotdog at the press conference, a lot of the toppings/condiments trail behind it. When the shot changes and the hotdog hits Mike, there are no condiments trailing behind it. (00:19:10)
Part-Time Friends / Bio Square - S2-E19
Other mistake: Bio Square: While Phoebe and Stinky are telling the class about their science fair experiment, just as Phoebe shares that it was in honor of her hero, "I.P. Pavlov," watch as Stinky's eyes move off to the side of his head, then return to normal.
What Does Blue Want to Make? - S1-E15
Visible crew/equipment: A boom mic is visible when Steve starts singing "We Just Got A Letter."
First Kiss - S1-E17
Visible crew/equipment: At the end of the episode when Harvey hops away, a boom mic is visible. (00:21:55)
Continuity mistake: The bottle of orange soda on the breakfast tray Dick tries to bring to Mary changes to a bottle of alcohol (Jack Daniel's I believe) when he sets it down. It later changes back into the bottle of orange soda.
Midori no chikyû wa makasetoke - S1-E2
Other mistake: When Yurika restarts the Nadesico, one of the screens pop up with a huge congratulatory "SAFATY ROCK OFF." (00:18:05)