Best horror movie mistakes of 1991
Continuity mistake: When the killer rips his mask off to expose his face to Maggie, his eyes go from brown to yellow between shots. It is explained later that his yellow eyes becomes brown thanks to colored contact lenses, but the killer does not remove any contacts when rips off his mask.
Visible crew/equipment: During the scene where the grandmother and the monsters stop at a variety store in the tinted bus a camera man can be seen. As the bus pulls away, you can see the camera man standing there filming the scene quite clearly in the reflection of the bus windows as it pulls away.