When the family arrives at the hotel after walking through the woods, Melanie is wearing a different hat, and her hair is disheveled. When she walks into the lobby, she is wearing her original hat and her hair is perfect.
When James watches his daughter dancing through the window, the curtains are all the way closed. When he gets a ladder to climb up, the curtains are partly open.
When Trey and the pig play chess in the tub at the hotel, the arrangement of the pieces on the board changes between shots.
In the early scene of James and Nancy in bed, Nancy puts a pink sleep mask over her eyes. When James wakes her, she raises the sleep mask the top of her head. In a shot from over his shoulder, the mask is gone. In the next shot, the mask is back on top of her head.
Georgetown University is 2.8 miles from the White House, well within the restricted airspace zone. It's very unlikely that a plane would be allowed that close without being shot down.
Near the end of the movie, Wendy Greenhut tells Melanie that she inspired Wendy to apply to Georgetown University. It would've been impossible for Wendy to apply to Georgetown for the same class year as Melanie, who was on the waiting list. The application process was too far along.
The girls go to stay at a sorority house at the University of Pittsburgh. Sorority houses are illegal in Pennsylvania.
In one scene in Chief Porter's police SUV, part of the director's head is visible in the back seat, on Melaine's side.
The closest golf course to Georgetown University is the East Potomac Park Golf Course, more than 4 miles away.