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.
Character mistake: Dan mentions he's 66 years old. In a later scene, Darlene says to Dan, "You're 65 years old..."