Continuity mistake: In the film the Eye Creatures have landed their spaceship in a field during the night and the Army has been called in to survey the spaceship. A soldier gets on top of the space ship and starts using a welding unit to try and open it and it's bright and clear out. The temperature of the welding ignites a fuse on the spaceship which causes the ship to explode. When the scene shows the spaceship blowing up it's now pitch black outside.
Other mistake: Dean Jones and Connie Stevens are riding in a gondola of a skyway ride at a seaside amusement park. The gondola they are in is obviously on a studio soundstage. It is much larger than the gondolas shown in the rear-screen projection. In addition, there are no riders in any of the other gondolas and the gears and cables of the ride make absolutely no sound.