Goofs

In Emily's house, she lays the .38 pistol down on her work bench and pours herself a glass of Jack Daniels and sits the glass back down beside the pistol and bottle. When her visitor pours himself a drink a minute later, same spot, the bottle has become a Dewar's bottle. Two minutes later, the Jack Daniels bottle is across the room on a low end table with the glass beside it.

Three minutes in, a noose is slung over a tree branch. The noose is shown dangling no more than 1ft below the branch. The noose swings back and forth but visibly stays at the same height in comparison with a branch directly behind it. The branch is far away. In the next shot the branches are much much closer to the noose. A priest climbs up onto something, approximately the height of a chair, to put the noose around his neck then steps of of what he is standing on (he does not jump) and drops out of frame farther than he climbed up into view. The shot pans up a good two to three feet and fails to show the branch that is previously established as being not more than 1ft above the priests head. This implies that there at least 3 feet of rope should be between the priest and the point of suspension. In the next scene the priest is revealed as being not substantially more than three feet down the rope and hanging near a low brick wall. The brick wall is more than two feet below the priest and there is nothing else for the priest to have climbed onto in frame. To hang himself the priest must have levitated as he ends up hanging higher than a chair could account for (even if a chair realistically fell out of shot behind the low wall).

The recently deceased have normal skin. But when they get resurrected, they have horrible skin.

The people of Dunwich are said to be descended from "Salem witch burners", although no accused "witches" were ever burned in Salem (most were hanged).

It is claimed that Dunwich was built on the ruins of Salem, Massachusetts. However, Salem still exists to this day.

Mary could not have been buried alive as she would not have survived the embalming.

Although the film is set in the United States, Tommy's van has its steering wheel on the right side, revealing the film's European origins.

When Father Thomas hangs himself, there is no evidence of him standing on anything to reach the noose.

When man puts makeup on dead girl in the morgue, we can see her eyelashes still moving.

Fake plastic head is visible in the extreme closeups of the intestine-vomiting scene.

Despite the movie taking place on Halloween (the day before All Saint's Day) in Massachusetts (the site of old Salem), there is no fall foliage or other evidence of the autumn. The plants are in full summer green, and there is Spanish moss in the cemetery.

When the Peter Bell character is talking to the policeman he refers to Sgt. Clay twice in the conversation. The first time he correctly calls him Sgt. Clay. The second time he incorrectly calls him Sgt. Bell.