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)
Sid the Vampire Slayer / Big Sis - S5-E3
Other mistake: Sid the Vampire Slayer: While Sid stands in front of the mirror and points his rubber sword at Arnold and Stinky, the two ghoulish vampires, Arnold asks him, "How can we be vampires if we have reflections?" So when Sid is aware of his mistake, Arnold's eyes disappear and reappear in his reflection mid-shot.
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."
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)
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)