Trying to convince Darlene to get the family together for Thanksgiving, Dan tells her "We'll watch 'Planes, Trains, and Automobiles,' and by the time John Candy says 'Those aren't pillows,' we'll be a whole family again." In fact, Steve Martin delivered that line in the film. It does seem inconceivable that everyone connected with a contemporary sitcom that's still in production would make such an obvious mistake, so perhaps this was done on purpose for comic creative writing, or something of that nature.