Screenwriter
Philip Eisner acknowledged that
Warhammer 40,000 influenced the story.
[10] In the setting of
Warhammer 40,000, spaceships travel the galaxy by passing through "the Warp"—a parallel dimension where faster-than-light travel is possible, conceptually similar to "
hyperspace" in
Star Wars, but which is also inhabited by evil spirits that can infiltrate the ship and possess the crew if said ship is not properly shielded. Fans consider
Event Horizon to be an unofficial prequel to
Warhammer 40,000, when humankind discovers the Warp and learns of its dangers the hard way.
[11]