Visible crew/equipment: Carol and Dr. Marvin drive by the "Operation Sky Hook" sign and you can see the shadow of the camera on it as they pass. (00:02:50)
Continuity mistake: Between the second and third shot of the movie the cockpit of the jet changes in the close-up. (00:00:20)
Factual error: This mistake involves the scene with the "translating computer". This scene was actually filmed at the University of California's Engineering Lab, and the machine (called a differential analyzer) really was in use at that time. A photo of this exact machine can be seen in the November, 1951 issue of 'Radio and Television News' on page 70. Here's the mistake: In front of Dr. Marvin, is an X-Y plotter, used to plot graphs from the machine. When the camera zooms in on it, the camera now shows a pantograph, which is a mechanical device to duplicate drawings or sketches. Out of camera view, a crew member is writing the message, and the 'output' end of the pantograph is then shown doing the 'writing.' That machine (or any computer in the 50's) would be incapable of translating a foreign language, let alone an alien one. (01:00:55 - 01:01:30)
Continuity mistake: As they sit enjoying Carol's barbecue the umbrella on the table behind them is tilted in a different direction between shots as a soldier drives up in a jeep with a message for Dr. Marvin. (00:13:15)
Continuity mistake: One of the three trucks used in the movie with the magnetic interference units on them has a distinctive kink in it's dish, and we see this truck destroyed by the aliens. Several shots later when the battle is over this truck is back again. (01:19:05 - 01:20:55)
Continuity mistake: We see the head of the alien up close twice and each time the gravel underneath is raked differently. (00:56:25)
Continuity mistake: After they've destroyed the alien craft spotted flying around inside of the Belmont lab, Dr. Marvin and the others decide to pack up and leave. Even though the sound has been edited out, the car and truck are already running with their headlights on before anyone gets into them. (00:51:50)
Other mistake: As they travail to The Pentagon in Washington, Carol and Dr. Marvin sit in the exact same mock-up of an airplane's interior that we saw earlier in the movie when a UFO passes in front of it. (00:00:45 - 00:27:00)
Continuity mistake: The Motorcycle cop that is taken up into the alien spaceship with them asks, "What team has won the most World Series?". When he asks the question he takes his hat off which leaves a dark impression on his forehead, in the next shot it's gone. (00:41:40)
Continuity mistake: After they pull over to the side of the road to look at the UFO, Dr. Marvin gets back into the drivers side of the car as Carol slides unobstructed from the drivers side over to the passenger seat. In the next shot the tape recorder is sitting there between them. (00:05:55)
Continuity mistake: After they pull over to the side of the road and look at the UFO, Dr. Marvin gets back into the drivers seat and hands Carol a Chesterfield from his shirt pocket. In the previous shot he didn't have anything in his shirt pocket, in fact he didn't even have a pocket on his shirt. (00:06:00)
Continuity mistake: The UFO flies right over the cockpit of a United Airlines jetliner but does not leave a shadow. (00:00:45)
Audio problem: After Prof. Kanter is incinerated by the alien's beam, Maj. Huglin points his shotgun at the alien and fires. If you look closely he pulls the trigger the first time and the gun misfires and you can see the recoil but not hear anything. (00:55:45)
Continuity mistake: Dr. Marvin and Major Huglin leave The Internal Security Commission meeting together and drive from The Pentagon to the doctor's hotel. Even though we just saw Carol and Dr. Marvin fly into Washington in an airplane he's driving the exact same make and model car that they were in at "Operation Sky Hook". Even the California license number AV-35-B7 is the same. (00:30:00)
