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: During the alien's assault on the ship, one crewman is seen near the spaceship's stairs firing a weapon. However, the weapon is pointed at a forty-five to sixty degree angle - at this angle, he would hit the bottom of the ship, not the alien that is much farther out.
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: When Luther Blair rescues Captain Larson from his cell towards the end of the film they are both shown exiting the cell with pistols drawn and ready. When the shot cuts to the corridor outside both their pistols have now disappeared from their hands.
Continuity mistake: After his meeting with Julia, Winston at home opens the drawer and in a close-up pulls the diary out from under a stack of papers which he lifted with his left hand. The angle changes, and his left hand is on the edge of the drawer, and not supporting the papers any more, nor any paper is visible. There's also a pen on the table that should have been visible before, but wasn't there. (00:36:25)
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)