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)
Factual error: The aliens request a meeting with Dr. Marvin on the shores of the Chesapeake Bay, near Washington DC. However, the shot of him driving along the shore line shows mountains in the background, which don't exist in Eastern Maryland. (00:35:13)
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.
Visible crew/equipment: At the climax, when the creature escapes and begins throwing furniture around, you can clearly see the wires attached to the pieces of furniture.
Factual error: During the meeting concerning Godzilla, one of the scientists incorrectly states that the Jurassic Period was 2 million years ago. The Jurassic Period lasted from 180 to 135 million years ago. (00:29:40)
Other mistake: When the title card is shown, the copyright year is shown as 'MCMXXXIV' (1934). It was released in 1956 (MCMLVI).
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)