Continuity mistake: When the police find Nick, his body is half submerged in the water. When the cop points him out, he's on top of the rocks, not covered by any water at all.
Continuity mistake: At the end of the film, Victor tells Nick to write 'hey Annie' on plane's wing to send her a message. When Nick throws the plane and the camera shows it flying around, the words that Nick wrote are nowhere to be seen.
Other mistake: About a third of the way into the film when Nick leaves school and is running home he gets hit by a car and run over by a truck. Before both events the vehicles horns can be heard, as if the drivers are warning Nick to get out of the road. If Nick was invisible there would be no reason for them to honk their horns at all.nap