Continuity mistake: When Roseanne & Jackie talk about Arnie, they act like they haven't known him long. Jackie even states, "I don't know him." Yet, in episode "Why Jackie Becomes a Trucker," Jackie sleeps with Arnie. Roseanne says all the girls made a pact in high school that none of them would ever sleep with him.
Continuity mistake: Part 2: When Beck is visiting, Aaron Jastrow's wine glass refills itself several times between takes, even though he hasn't poured any more wine. (00:42:00)
Continuity mistake: When Miss White is writing Mrs. Heimer on the chalk board, the camera shows Kevin/the class, when the camera comes back to her, she has a different sweater, hairstyle, and her name is written in a different spot. I'm not sure if this is some kind of flash to when everyone comes back to school after summer, or an error.
Episode #4.9 - S4-E9
Continuity mistake: Later when the crews are trapped C389GFC is arriving as a new appliance even though it has already been there.