John Carpenter has said that this film, with its creatures hidden in the clouds, was the inspiration for his film The Fog (1980).

Featured in the first episode of Mystery Science Theatre 3000 (1988).

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.

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.

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."

Last film produced by Southall Studios, one of the earliest studios in the UK.

The fighter pilot during the final battle with the creatures gives his call-sign as "Jolly Roger." Whilst 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, then the pilot was the best of the best.

Warren Mitchell was an 11th-hour choice after the original choice went on holiday (interview in book X Cert).

The cloud effect was done by nailing a piece of cotton wool to a photograph of a mountain.

Quentin Lawrence had also directed the original TV mini-series, which was more than double the length of this movie version - and did not include the film's central character, "Alan Brooks", in its cast-list.

The light aircraft shown mid way through the film is a Morane-Saulnier MN 502 Criquet - based on the WW2 German Fieseler Fi 156 Storch

Inspired the song "The Crawling Eye" on the Misfits album Famous Monsters.