Continuity mistake: In the end of the episode whilst the families are eating lunch at the picnic table there is a lot of plates of food and glasses on the table. Towards the end of the scene Brian says "I guess some mysteries are better left unsolved", there is a wide shot after he says this and every plate and glass from the table has disappeared. (00:21:25)
Factual error: In all the scenes where Peter wrecks Cleveland's house and Cleveland is in the bath, the tub always slides easily out of the house with Cleveland in it and onto the ground. There are no pipes or any kind of plumbing visible on the bathroom floor where the tub should have been connected.
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)