Audio problem: In the episode where Homer is hosting gay marriages, at one point Homer is strangling Bart and tells Lisa to hold his spot. You can hear Lisa say, "Why you little," and you can hear Bart choking, but neither of their mouths is moving.
Continuity mistake: When Marge arrives home complaining that she is too tired to talk, there is an alarm clock on Homer's night table. When first shown it is a black electric clock, but when it is shown in the very next scene, it is an old orange one. Only a few seconds passed between these scenes, meaning there was no time for anyone to change it.
Continuity mistake: When Homer rings the doorbell of the Flanders' former house to visit the new neighbour, it moves downwards on the door frame. In the first shot it lines up with the gap between the lock and the doorknob, but in the next shot it is beside the doorknob, and in other shots in the episode the doorbell isn't even there. Also, the glass panels on both sidelights line up with the door differently between shots.
Continuity mistake: As the Simpsons are in the cinema watching "Kosovo Autumn" you can see there is a seat next to Homer to the right of screen. When Homer starts complaining about the film but cannot leave because he is stuck in his seat, the shot changes and we see him from behind however the seat that was next to him has disappeared.
Continuity mistake: For "Home Away From Homer": Bart looks out his bedroom window and sees the college girls doing sexual actions in the Flanders' spare bedroom. But, there is never a window in Bart's room that could possibly face the Flanders' house. [Bart's window in many episodes does face Flander's house but in other episodes like "Bart's Friend Falls In Love" and "Bart The Mother" it faces the treehouse which is the backyard of the house.]