In one scene, Dr. Kelston refers to the "Lubbock Lights" and to a "Captain Mantell." These were-real life U.F.O. events that created a nationwide sensation in their day. The photographs shown by Dr. Kelston are actual photographs of the Lubbock Lights that appeared in newspapers and magazines.
The genesis of this film was when the wife of writer John Tucker Battle woke him up one morning to recount a vivid and disturbing dream she had of Martians invading Earth. He had her tell him as much as she could recall, and he developed the rest of the story from there.
Several well-known actors appear in very small parts. Among them are: Todd Karns playing Jimmy the gas station attendant, who was also in It's a Wonderful Life (1946) as Harry Bailey; Lock Martin as the Martian mutant carrying little David in the underground tunnel, who played Gort the robot in The Day the Earth Stood Still (1951); Milburn Stone, who played an army officer searching the sand dunes with a detector to locate the underground Martians, and who later played Doc Adams on the long-running western series Gunsmoke (1955); Barbara Billingsley, playing Dr. Kelston's secretary who was also Mrs. Cleaver in Leave It to Beaver (1957); Robert Shayne, who plays a scientist almost killed by the Martians and played Inspector Henderson on Adventures of Superman (1952); and Douglas Kennedy, who plays a policeman taken over by the Martians and who also had his own western series, Steve Donovan, Western Marshal (1955).
The eerie sandpit choir chant was done by a choral group made up of eight men and eight women, and was further enhanced with echo in post-production to give it a more haunting and ethereal quality.
Among the cost-cutting measures made during filming was the elimination of Cricket, David's dog. The use of animals during filming almost always takes more time, and therefore more money, a luxury that director William Cameron Menzies didn't have.