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)
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)
