Continuity mistake: Chris O'Donnell and Drew Barrymore are leaving the small town of Truth or Consequences, New Mexico, and they show the outskirts of the town as White Sands, when actually White Sands, New Mexico is about 2 hours away.
Continuity mistake: At the end of the film when Drew Barrymore is on the white sand threatening to shoot herself, in one shot she has no mascara smudges under her eyes. Then the next shot shows large mascara smudges under her eyes, and in the next shot they're gone again.
Deliberate mistake: When Matt is spying through the telescope on Casey's argument with her parents, you can hear Casey yelling "No no no" and hear her bedroom door slam, etc. This is all from Matt's point of view from the telescope - it would have been impossible for him to hear any of that, being such a far distance all the way across the lake.
