Composer and musician Frank Zappa made a tribute to "It Conquered the World" in his album, "Roxy & Elsewhere" (1973). In the introduction of the song "Cheepnis", Zappa tells the audience that he loves monster movies. "And the cheaper they are, the better they are". Frank Zappa describes this movie as a perfect example of monster movie with its alien with an "inverted ice-cream cone head with fangs". He describes one special scene when the "monster came out of the cavern" and he could see the technicians pushing the creature over the rail. "This is cheepnis", Mr Zappa concludes before playing the song.
Originally, "Beluah" was built as a squat, flat-topped creature, under the mistaken belief that Venus had higher gravity than Earth's. (It doesn't; Venus' gravity is slightly less than ours.) When it turned out not to be imposing enough - and to actually be shorter than leading lady Beverly Garland - a tapering conical top was added to it.
Paul Blaisdell's friend Bob Burns restored the costume when it came into his possession long after Blaisdell's death. The photographs of it in his book "It Came From Bob's Basement" reveal it to be beet-red in color.
Peggie Castle was originally cast as Joan Nelson, but had to pull out of the project shortly before filming began. She was replaced by Sally Fraser, who did it as a favor for director Roger Corman, a friend, even though she was five months pregnant at the time.
Paul Blaisdell, who designed, built and portrayed the alien in the movie, affectionately dubbed his creation "Beluah". It is easily the most popular monster of Blaisdell's oeuvre among his fans as well.
Though the film was later featured and mocked on an episode of Mystery Science Theater 3000, the writers praised the performance of Beverly Garland. She was invited to (and attended) the first convention dedicated to the show, and show writer Paul Chaplin included a short essay extolling her acting ability in this film: on the scene where she hurls insults at the monster, Paul wrote, "In that moment she IS a woman enraged at a pickle."