Continuity mistake: When the oldest son, Patrick, is in the back yard with his father, Patrick is shown with a beer in his hand. The next shot is Patrick's dad offering him a beer and telling him not to act like it's his first time.
Factual error: This movie takes place in 1976, but you can see the 900 N. Michigan building in a shot of the Chicago skyline. This building was not built until the early 90s.
Visible crew/equipment: Early in the film just after the family arrives at Church, everyone piles out of the station wagon. A few seconds later the rear door opens and almost immediately closes again.