The Universal-International make-up department submitted two alien designs for consideration by the studio executives. The design that was rejected was saved and then later used as the Mutant in Universal-International's This Island Earth (1955).
Although credited to Harry Essex, most of the script, including dialogue, is copied almost verbatim from Ray Bradbury's initial film treatment.
The opening aerial shot is of the Mojave River Narrows in Victorville, CA. As the scene opens, over the rocky hill the town view is looking generally north-west up D-Street (Hwy-18) in 1953 downtown Victorville. The railroad tracks and Mojave River are to the right, and U.S. Hwy-66 (7th Street) turns left off of Hwy-18 and travels south-east through town towards the Cajon Pass. The airport scene was set at the old Apple Valley Airport next to Hwy-18, and across the highway from the old Roy Rogers Apple Valley Inn. Additionally, Sky King's plane, 'Songbird', was based from this same airport around this time.
According to a magazine article, the "bubble" effect when the audience is seeing things from the alien's POV was achieved by blowing a specially formulated "tough" bubble around the camera lens. These shots were kept short since the bubbles only lasted a brief time.
This was one of the few American movies from the 1950s to place its credits at the end rather than at the beginning.