Plot hole: The whole point of Darry going down the pipe near the beginning was because he couldn't see the bottom of the pipe. However, Trish can make out his shock when he notices the body. Darry's flashlight is not providing the light in this scene as the light is coming from the tunnel. (00:21:05)
Revealing mistake: When the demon breaks into the jail and the cop is standing behind him. When the camera turns back on to the demon, if you look close you can see the zipper in the left hand side of the demon's suit. (01:08:45)
Continuity mistake: About 10 minutes into the movie, when the truck is chasing the 2 college students in the car and starts ramming them, the bumper and the trunk is smashed in. The shot changes and shows the car's rear end and it is in perfect condition. This repeats at least 3 times.
Other mistake: When Darry is in the basement under the church, Darry is laying on the floor surrounded by a circle of sunlight appearing through the pipe. Then follows a series of cuts between Trish at the open end of the pipe, and Darry. Why do we not see a silhouette of Trish on the floor rather than a perfect circle of light?
Continuity mistake: The police station that they stop at is in a very out of the way rural community with only a few people in the jail. However, once the demon enters the jail and the alarm is sounded there are at least 20 cops on duty - all at the station in the middle of the night, in the middle of nowhere.
Factual error: When the kids are getting hit from behind by the truck, cut to a side shot of them in the car, the boy's body moves forward, while the girl's body is more properly propelled in a backward motion relative to the car. This happens several times.
Continuity mistake: When the college students pull into the gas station their right tail light is out, but when they are being followed by the cops the left tail light is out.
Continuity mistake: When the main characters visit the house of the old woman with the cats, she comes out and aims at the monster with a double-barrelled shotgun, and fires one shot. Then when she goes back into the house, two shots can be heard in quick succession. She must have re-loaded the empty barrel quickly...
Continuity mistake: There are at least two different 1960 Chevys used in this film. There is a noticeable difference in the front bumpers. Notice the front bumper area just below the headlights. The first car used has a plain straight bumper, the second one has little chrome trim riser mounted just below the center of the headlights. The second one first shows up at the cat lady's house. The lower tag pan also changes.
Visible crew/equipment: When the police are following the two kids to the old church, the first shot shows the kids driving but when the camera is slowly going to the cop car on the the door you can see equipment.
Continuity mistake: After the monster eats the cop's tongue, it's supposed to be the nighttime during the car scene, but the back window on the driver's side is rolled down and as the scenery goes by it is apparently broad daylight.