Other mistake: The filming of the spycam at the dance doesn't make sense. Grandpa and Judy are roughly the same height. The spycam was placed in his shirt pocket. Yet, when he looks over at her, her head is right in the middle of the shot, when in reality it would have been much higher up, and likely out of frame.
Factual error: When Kyle and Kerry go to the arcade, they look around to see which game they want to play. Kyle suggests the dancing game, which, although the name is not displayed, is Dance Dance Revolution. The current screen is the song select, which only appears after a token has been inserted and the game has started. It takes at least two presses of the start button to get to that screen, yet Kyle still feels the need to insert a token for some reason. Also, although this is trivial, the difficult setting on which they play is Beginner, which is laughably easy and doesn't require any of the theatrical dance moves that Kyle and Kerry perform.