The plane crash was from remote control experiments made by the Air Force.
Due to the film's meager budget, cast members had to perform their own stunts with little preparation or training. According to Robert Hutton, this almost led to disaster at least once during the shoot. John Agar very nearly overturned a jeep carrying himself and Hutton during a scene in which he was instructed to brake and swerve sharply. The jeep tilted onto two wheels and very nearly toppled over with the actors inside.
The decision to make the aliens invisible was more than a simple plot point. Producer Robert E. Kent insisted that the alien invaders remain unseen in a cost-saving measure. Without costly special effects, extras, and additional sets, the producer's decision helped to balance the film's otherwise severe lack of funds.
The footage of a car crashing into an electrical substation is recycled from the end of Thunder Road (1958).
Bronson Canyon in Los Angeles served as the location for the stronghold featured in the last third of the film.
His role as Adam Penner was the final role for Philip Tonge. He died on January 28 1959 before this film went into release on May 15 (shooting began December 11 1958).
United Artists released this as the top of a double bill with The Four Skulls of Jonathan Drake (1959). Both films were directed by Edward L. Cahn, and despite each film listing a different production company, Premium Pictures and Vogue Pictures, both were actually produced by the same company.
The name of the character "Dr. Karol Noyman" (played by John Carradine) was recycled by screenwriter Samuel Newman from an entirely different character in his film The Giant Claw (1957) (played there by Edgar Barrier).
The Invisible Invaders (1959) Blu-ray released in July 2016 by Kino Lorber features a full-length audio commentary by film historians Tom Weaver and Dr. Robert J. Kiss.