It Conquered the World (1956)

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.

Revealing mistake: Toward the end of the film, when Claire Anderson enters the cave where the monster is waiting, she passes a distinctive rock formation. In a later scene, where she is going further into the cave, she again passes the same rock formation.