Continuity mistake: At the start of the film, the dog is seen going from room to room looking for food. Just before he goes into Dana's room, someone can be seen through the crack in the door, moving from left to right.
Continuity mistake: When they are all outside and MacReady has separated the three most likely suspects and orders that they be tied down and tested, he comments at that time that they are to be hit by a storm in six hours. Cut to the scene where Mac is dictating into his recorder and he comments that the storm has been hitting them hard for 48 hours. However it is the same night and at best, maybe only an hour has passed.
Continuity mistake: When Debbie is killed in the hammock, in all shots of her, the quilt covering the hammock net has patterns sown on it, such as flowers. However, in the closeup of Debbie as the knife comes through her chest, the quilt covering the hammock is the same one as before, however you can now see it is suddenly the other side of the quilt. (01:02:25)
Continuity mistake: When in the rowboat, Adrienne Barbeau's t-shirt is white in some shots and blue in others. It is not the lighting - it is plainly two different coloured t-shirts.
Continuity mistake: When little Buddy and his family are being murdered by the use of Little Buddy's Pumpkin mask, the Silver Shamrock tag on the back of the mask disappears and reappears several times.
Continuity mistake: When Coach Jana is cut across the chest by Russ, blood gets on her tee-shirt that says "Speedo", between the two E's. In the next shot, as she falls to the floor, that blood has vanished. (01:07:45)
Continuity mistake: Sand on Harry's faces disappears between shots as Richard buries him.
Continuity mistake: During the first rape scene, Carla is slapped in the face drawing blood and a pillow is placed over her face. After the scene, however, there is no blood on her face or the pillow.
Continuity mistake: At one point in the film, the wingspan of Q is mentioned. Later on, its length is mentioned. The monster is twenty feet longer than its wingspan.
Continuity mistake: When the kids are in their room, the paint brushes come flying out of the red and green cans, but as the brushes are painting on the wall, they are both covered with only red paint.
Continuity mistake: When Sheriff Stevens is arresting John, he has his hand on the back of John's shirt collar as he lifts him up. But in the next shot, his hand is grabbing John's hair.