From The Grindhouse Cinema Database
- The robots Gog and Magog were operated by midgets.
- The centrifuge scene was filmed at USC. The actors became sick and were replaced by dummies.
- As of April 2005, only one complete dual-projector stereoscopic 3-D print is known to exist anywhere in the world. The Left and Right prints do not match: the color is severely faded on one side, but the film is still viewable in 3-D.
- The Hoover Dam's turbines were photographed on glass to provide projected backgrounds to some of the lab scenes.
- The base emitted signals to confuse copter nav And base is underground
- Director Herbert L. Strock had very poor vision in one eye and consequently was unable to properly gauge how the 3-D effects were, and had to rely on others to tell him. Coincidentially, André De Toth, who directed House of Wax (1953), arguably the most famous 3-D film, only had one eye and could not see the 3-D effects at all.
- This rather talky item is from a story by Ivan Tors, producer of TV's Science Fiction Theater, pretty talky in itself. For all that, English was not his native tongue.
- William Schallert was paid $250 for two days' work.
- Base is underground, maze style interior & emits signals that jam copters navigation so pilot cant find base despite repeated trips, see base interior plan on wall.
- The shooting schedule was fifteen days on two sets at Hal Roach Studios, with exteriors at George AFB (Victorville).
- Herbert L. Strock got in trouble with the Director's Guild for combining his directing and editing credits.
- Shot in 3D, but released mainly in regular 2D.