The pilot in the stock footage sequences is Chuck Yeager.

The astronaut/monster suit was so stifling and dangerously thermal, it could only be worn for a few minutes at a time.

Bill Edwards' voice is dubbed.

John Croydon wrote Grip of the Strangler (1958) and this film back-to-back.

The Y-12 was portrayed by the Bell X-1A, which was carried and launched by a Boeing B-29 Superfortress. Shortly before launch, test pilot Ed Schoch is momentarily seen closing the cockpit canopy of a McDonnell XF-85 Goblin aboard another Boeing B-29 Superfortress. The Y-13 was portrayed by a Bell X-2, which was carried and launched by a Boeing B-50 Superfortress, although the X-1A is seen being loaded into the B-29 at one point.

This film is part of the Criterion Collection, spine #365.