Martin Sheen agreed to star in this movie because he always wanted to star in a comic book movie. He later played another comic book role, Uncle Ben in El Sorprendente Hombre-Araña (2012).
John Leguizamo ate live waxworms on pizza for this film. He then vomited immediately after the take was wrapped.
Michael Jai White found Al Simmons' character appealing; he described Spawn as "the most tragic character I've encountered in any cinematic production." He says it was a challenge to make audiences sympathize with a government assassin who comes back from hell. White had to endure two to four hours of make-up work, including a full glued-on bodysuit, yellow contact lenses that irritated his eyes, and a mask that restricted his breathing. He said that his long-time experience with martial arts helped him endure the uncomfortable prosthetics, giving him "strong will and unbreakable concentration."
Todd McFarlane: When Spawn is fighting the Violator, he encounters a frightened homeless man. This is the creator of the Spawn comic book.