Continuity mistake: As Stewie is about to eat his brisket (just before he throws it at Meg) he is cutting part of it off. Just as he cuts through the shot cuts and you can see the brisket is now back in one whole piece. You can also see the mashed potatoes change from white to green.
Continuity mistake: When they are at the football game and Meg and the flag girls come out, and after Lois says, "Oh Peter, isn't she beautiful?", Peter's hot dog is yellow and has ketchup. But after he throws it on the field, it is back to normal. (00:07:30)