Factual error: There's a Lumber Liquidators sign under the Skate Off sign at Sweetwater Skating Ring. Lumber Liquidators wasn't created until 1993. The movie is set in 1978.
Continuity mistake: When X's father comes in and initially asks Boo if the skateboard is his, Boo is about to drink a Yahoo. The camera pans to X's father as he asks a question. The shot then goes back to Boo and he no longer has the Yahoo; he is holding a joystick for a video game.