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)
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."
Helga Blabs It All / Harold the Butcher - S3-E1
Continuity mistake: Helga Blabs It All: While Helga hides in the overhead ventilation shaft, the vent cover has either four, five, or six slat openings in various shots.
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)