Anecdotes

Shot without sound. To avoid having to sync a lot of sound in post-production, the actors turned away from the camera when speaking, and cupped their hands over their mouths when shouting.

According to Anthony Cardoza, the rabbit at the end was not scripted; a wild baby jackrabbit wandered into the shot.

The setting was based on the real-life Yucca Flat, which has been called "the most irradiated, nuclear-blasted spot on the face of the earth." The actual shooting locations were in California: Santa Clarita (desert scenes), Saugus (airplane scenes), and Van Nuys (opening scene interior). In 1970, 86 workers were exposed to radiation during the Yucca Flat Baneberry Test. In March 2009 "Time Magazine" identified the accident as one of the world's worst nuclear disasters.

Since no audio was recorded during principal photography, during scenes in which firearms are used, the muzzles of the guns are usually out of shot when the weapons are fired. Also, in scenes of gunplay, many characters appear at first to have suffered life-threatening bullet wounds, only to appear in later scenes fully recovered with no visible signs of having been wounded.

Tor Johnson's final starring role. He had one more uncredited role in Head (1968).

Coleman Francis: [coffee as calming influence] The patrolmen relax by having coffee.

Coleman Francis: [location] Yucca Flats airstrip.

Coleman Francis: [props] Light aircraft used to transport main characters.

Coleman Francis: [location] Yucca Mountain