Continuity mistake: Just before the kitchen mistake, Marge walks through the doorway from a room with a piano, beside a bare wall, and on the piano are two frames and music sheets. But when Marge turns the jar upside down, there is a large picture on the wall beside the piano, and the music sheets and frames have disappeared from the piano.
New this month Continuity mistake: In "The Thing and I": After the kids have found Hugo in the attic, when Marge and Homer return home, both front door knobs (inside and outside) do not have backplates, but once Hugo escapes both door knobs have backplates. The two backplates vanish and reappear repeatedly in following shots. It's funny because when they leave to search for Hugo, Homer shuts the door with no backplates, but then Bart uses a key in the backplate to lock the front door.
New this month Continuity mistake: At Mo's, when Grizzly Shaun is talking to Smithers about Mr. Burns, Smithers is wearing a grey suit, but when Mr. Burns says "A good old fashioned lemon party", Smithers is wearing his usual outfit, which turns back to the grey suit in the very next shot.