(at around 24 mins) Christie has earrings on during her nightmare, they disappear when she is outside walking to the pool, but reappear when she enters the pool.
When the pair stops making love in front of a fireplace, light in the scene has changed between 2 continuous shots.
Christie is not as wet as she was when exiting the pool when she enters the house not a minute later.
(at around 1h 11 mins) When Paul injects Christie as he presses the needle to her arm you can see the needle move further into the syringe and not into her arm.
When Paul is embalming the young girl early in the film, her eyelashes move whenever he touches her body with the probe.
Josh can be seen moving while being dead at the end scene.
Obvious fake flash for the embalming scene of a dead girl when her skin is punctured.
(at around 17 mins) After Christie drops off Greg at the police station the crew is visible in the rear driver's side window as she departs.
At 1:15:37, just as Bill Paxton's character tosses a sheet over Mary Beth McDonough's character on table, there is a visible flash of light coming from the right side of the screen along with a click that indicates a photographer on set likely snapped a still shot while filming commenced.
When Greg is arguing with his mother and father about Mr. Andrews in the flower shop, a shadow of a person at the right side of the screen can be seen appearing, probably a cameraman or a crew member.