Screenwriter Bruce Joel Rubin saw this film as a ten-year-old, and has cited it as "the beginning of the emergence of philosophy" in his life. In The Dialogue: An Interview with Screenwriter Bruce Joel Rubin (2007), he explains that right after he and a boyhood friend saw the film, they spent hours discussing the end of the world. Rubin mentions this memory while explaining that Steven Spielberg approached him to do the screenplay for a remake of "When Worlds Collide," and that it eventually evolved into Deep Impact (1998), with Rubin credited as one of its two writers.
There is a shot toward the end of a group of people sitting around a country store listening to the radio. Among them the little boy and dog later rescued by helicopter. The same shot shows up in The War of the Worlds (1953)
The differential analyzer, a mechanical analog computer seen in this film, was shot at UCLA (the same footage had appeared earlier in Destination Moon (1950)). It was built in 1947 by General Electric at a cost of $125,000 ($1.5M in 2020). By the time of this film, UCLA had a total of four of these machines.
The rights to the story by Philip Wylie and Edwin Balmer were originally bought in 1933 by Paramount, when director Cecil B. DeMille was planning a related project called "The End of the World." DeMille had hoped to rush the project into production after filming wrapped on This Day and Age (1933), but the script was never even written and the studio scrapped the project.