Filmed in a house called "Cliff House" designed by famed architect Frank Lloyd Wright. It was the home of the film's producer/writer/director, Arch Oboler, and sat on his 360-acre ranch in the Santa Monica Mountains along Mulholland Highway. Outdoor scenes were filmed on his property as well as other nearby locations in the Santa Monica Mountains. The "Cliff House" was burned to the ground - with only the foundations and chimney remaining - in the 2019 "Woolsey Fire," which swept through the area.
According to TCM's Robert Osborne, this is the first feature film to depict the aftermath of a nuclear holocaust.
The verse that appears on screen just after the title card and footage of atomic blasts is from Psalm 103:16 from the Bible (King James Version): "The deadly wind passeth over it / And it is gone; / And the place thereof / Shall know it no more..." Note the insertion of the word "deadly" which does not appear in the Bible.
In the 1994 book _Attack of the Monster Movie Makers_ by Tom Weaver, Phipps asserts in an interview that Oboler had already cast Leo Penn, future father of Sean Penn, as the lead and was looking to fill the role of Eric, the climber, when he asked Charles Laughton, "Who's your best person?" Laughton recommended Phipps, who was playing Petya, the perpetual student, in a stage production of Chekhov's "The Cherry Orchard" that he was directing, so Phipps had the scraggly beard. All ready to test for Eric, Phipps was surprised when Oboler said he wanted him to test for Michael, adding "nothing's set in concrete." The director liked Phipps for the lead, so he paid off Leo Penn.
The beach scene where Eric washes ashore was filmed at Westward Beach. This was the same beach where Charleston Heston encounters the ruins of the Statue of Liberty in "Planet of the Apes" (1968). In the long shots, the rocks visible in the distance were to the left of the statue.