When the vampire attacks atop the roof of the car driving down the highway, he wasn't on the roof in the set up shot on the highway.
When impaled through the back and writhing, the swaying fence posts that pierced the dying vampire are obviously attached to his clothing.
During all scenes in the funeral home we can see over the top of the sets. Scaffolding, bracing beams, and the studio walls and ceiling are clearly visible. We can also see over the sets of the farm house living room as the body crashes through the window.
Equipment on the landing when Ted calls the funeral home. During same scene Marie ascends the stairs and must step over the filming equipment.
Movie lights visible above Ted's head on both left and right, as he stands up from making a phone call. They remain in the shot until he sits back down, and the camera tilts down.