Continuity mistake: Throughout Gob and Michael's conversation in the kitchen, the sandwich on the counter keeps changing position without being touched.
Continuity mistake: When Lindsay and Michael are talking about Maebe's grades, the test paper that Lindsay just put on the fridge door sits near a note about running out of milk. In the next shot, the items have moved and the test paper is now mostly covering the note.
Chosen answer: "The One Where They Build a House," S2E2.