When the receptionist at the motel drops her pastry as she hangs up she hastily puts her cigarette out in the ash tray before kneeling down to up the mess and it falls onto desk and is still burning however moment later when we see the ash tray again as she reaches her hand up to scrape the wads of destroyed pastry on the counter top her cigarette is in the ashtray and no longer burning.
When Decker and Lori meet in Midian, Decker takes off his mask. Before chasing Lori he puts the mask back on, with the mask's long neck flaps now hanging over his collar and necktie. But in the next shot, the neck flaps are neatly tucked underneath his tight shirt collar again.
When the Pathologist is removing the rifle bullets from Aaron Boone's corpse in the morgue, they are clearly brand new and have not been fired into anything. The bullets would show striation marks from being shot down the rifle's barrel. Many people believe the bullets should have "mushroomed" or flattened out when hitting Boone, but full metal jacket bullets do not mushroom like hollow points or soft point bullets.
Ashberry is warned about "claymores" positioned in the graveyard. These are a type of land mine with a distinct, slightly curved, upright rectangle shape. However, the camera cuts down to a hand grenade. On top of this, the grenade's light blue handle marks it as a dummy grenade, used for training.
When the camera slowly pulls away, over Boone's dead body in the field in front of Midian, you can see him blink after several seconds.
During the scene when the berserkers are loose, a man catches fire and stumbles into a bush. You can clearly see the bush is a prop as it falls over and sits back up.
For the 2014 release of the "Director's Cut" of the film, Doug Bradley re-recorded his dialogue as Lylesberg, as Morgan Creek originally had his lines dubbed over by a German actor for the theatrical release of the film in 1990, much to his and Director Clive Barker's dismay. The editors at Shout Factory missed an entire scene when restoring Bradley's voice for the new cut, and the unnamed second actor can still be heard.
When the doctor checked Aaron in the police cell, he could not find a pulse. He wouldn't because he was checking on the little finger side of the wrist. The pulse is felt most strongly on the thumb side. It should only be taken with the fingers, not with the thumb, for exactly the same reason. If you use your thumb you risk feeling your own pulse instead.