When Peter drives Meg home after she fails to pass her driving test, the initial long shot of the car instead shows Lois in the passenger seat of the car.
Stewie takes the satellite dish from the garage, but later on, the garage has disappeared.
When Peter is talking to Lois on the bed, his glasses appear, then disappear again after mentioning the lamp.
When the man who is riding the horse-drawn carriage comes up next to Meg, he is not close enough to her window to be able to be seen. In the next shot, however, he is parked right next to Meg's window.
In the Scooby Doo cutaway, it shows the whole gang with "The Murder Machine" in the background. But when it shows the whole gang again, the van is not there.
Stewie's plate disappears when Lois tells him that his broccoli won't go away because he doesn't like it.