John Carpenter has said that this film, with its creatures hidden in the clouds, was the inspiration for his film The Fog.
For its release in America the film was cut down to 75 minutes, because American distributors wanted to get to the monsters faster. The full running length of the film is 84 minutes and is fully restored on the DVD release.
It had been a TV serial before becoming a film, Laurence Payne and Stuart Saunders reprise their roles from the serial. In the original production, the creatures were called "Ixodes."
The Crawling Eye monster literally makes a cameo appearance in Stephen King's horror novel 'It'. The children run into the creature in the sewers during a 1958 segment of the novel.
The fighter pilot during the final battle with the creatures gives his call-sign as "Jolly Roger." While not an historical individual pilot, The elite VF-17 "Jolly Roger" squadron was famous for producing more ace fighter pilots than any other squadron in the history of WWII. During the period of this film (1958), the audience would immediately understand in context, that if "Jolly Roger" had been called in, that the pilot was the best of the best.
This was the last film produced by Southall Studios, one of the earliest pioneer film studios of the United Kingdom.