Continuity mistake: When Michael is lying on the couch at his mother's apartment, the blanket covering him hangs over the side of the couch in some shots, but from other angles does not.
Continuity mistake: When Michael, Gob and Lindsay are in the kitchen talking about throwing a surprise party for their mother, Michael puts down a can of Sprite on the counter in front of his bag. In the next shot, the can is next to the bag and the coat that was over the bag has also moved, without there being time for anyone to move these items.
Chosen answer: "The One Where They Build a House," S2E2.