Continuity mistake: As Miles and Sally drive away from the train station her hand is resting on the passenger side window. In the very next shot her hand is by her side. (00:03:40)
Continuity mistake: There is a "No Riders" sign that keeps appearing and disappearing on the window of the jeep, from one scene to another, fron shot to shot, throughout the entire film.
Continuity mistake: Before Dr. Marvin removes the helmet from the dead alien, Maj. Huglin is holding his rifle in his right hand. In the next shot he's using his right hand to remove the helmet. Then in the shot after that he's not touching the helmet at all. (00:56:15)
Continuity mistake: During the opening conversation between Butcher and his lawyer, the shadows on Lon Chaney Jr. switch place depending on the angle - in the shots with the camera behind him, the bars cast a shadow on his neck and side of the head that is not there in the frontals. (00:01:30)