Character mistake: Dan makes a reference to the movie "Planes, Trains, and Automobiles" (the movie he's planning on the family to watch). He starts a sentence saying "by the time John Candy says 'those aren't pillows'." John Candy did not say that line in the movie - Steve Martin did.
Continuity mistake: As Mark sits down next to Dan and reaches towards his backpack, in the very next shot he's pulling out a history book, even though he has not gotten anything out of the bag.
TyPageCharacter mistake: Dan mentions he's 66 years old. In a later scene, Darlene says to Dan, "You're 65 years old..."