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: As Homer is giving his speech to the dressed up monkeys, all of the monkeys are dressed in blue suits and you can also see there is one monkey next to the stairs on the stage. In the next shot of Homer leaving the stage there is now six monkeys, with only one wearing a suit and it is grey.
Continuity mistake: When we first see Willie standing by the Black Wall of field trips, the latest entry is at Willie's eye level. But when the angle changes, there are a lot more names on the wall, making the last entry appear just by Willie's chest.
Continuity mistake: The stocks that are put on Marge and Homer are fitted so that their head and hands are secured and cannot be removed. Whilst in Flanders garage and Homer is using the rotary saw to remove Marge's stock, Homer's stock is still secured on him but his arms and shoulders are through the stocks.
Continuity mistake: As Marge arrives home and sees the bullet holes in the door, the shot changes to a POV shot from behind the door and you can see there are some changes in the holes. The first change is there are three bullet holes on the right hand side which are all the same distance from each other, when she enters the middle hole has moved closer to the bottom one. The other change is the large hole in the middle of the door. On the bottom right hand side its shape goes from being a little irregular to a more round shape.
Continuity mistake: In "Terror at 5 1/2 Feet", when Milhouse decides that he is going to sit next to Uter, Uter all of sudden moves to the other side of the seat between shots.
Deliberate mistake: When Homer pushes the trampoline off the cliff, there is no rock below the falling trampoline. However, in the shot at the bottom a tall rock is visible which was drawn there on purpose for the trampoline to bounce off of, despite not being visible in the first shot.