Revealing mistake: Jeff Trent, Col. Edwards and Lt. Harper grab some guns and take a walk in the graveyard, and a prop tree almost falls over as Col. Edwards walks by and brushes up against it with his shoulder.
Continuity mistake: During Criswell's opening narration, the time of the story changes from taking place in the future ("Future events such as these will affect you in the future.") to taking place in the past ("what happened on that fateful day...").
Continuity mistake: When the police are driving to the cemetery, it is daytime and their car is a standard police car with lights and sirens. When they reach the cemetery, it is night and the car is an ordinary car, without lights and sirens, and a different colour.
Continuity mistake: When the flying saucers are spotted over Wash DC, the scene shows a rotating radar antenna. First it's rotating counter-clockwise, then in a subsequent scene it's rotating clockwise.
At the beginning Criswell reads, "Can your heart stand the shocking facts about 'Grave Robbers from Outer Space'?" This was the original title of the movie that was changed because of objections by the financial backers.