According to an interview with director Stuart Gordon, Arnold Schwarzenegger was to star as John Brennick since Arnold was a big fan of री-एनिमेटर (1985) in which Arnold's stunt-double, Peter Kent was a cast member. Stuart Gordon: "...it was Arnold Schwarzenegger that got me the job and it was because of Re-Animator. We used Arnold's body-double in Re-Animator. The first reanimated corpse is a guy named Peter Kent, Arnold's double. He's got those big muscles. He got Arnold to see Re-Animator and Arnold liked it so much that he had a screening of it in his home, inviting all of these people, including producer John Davis. John had the rights to Fortress and Arnold was going to do it. For some reason, I'm not sure why, Arnold finally decided that he wasn't going to do the movie and dropped out. They had a big budget, probably like 60 million, 70 million dollars, which was a huge budget in those days. Now it sounds small. [laughs] Anyway, he dropped out and the budget went down. They cut the budget to about 15 million dollars."
Much of the film was shot on location at a prison. The cast and crew had to sign waivers affirming that they would not be rescued if the inmates took them hostage. At one point, a prison official gave several cast members safety vests to wear for protection, but promptly told the horrified cast members he wasn't sure it would help in case of a riot because "they usually go after your eyes anyway."
Due to the fact that star Christopher Lambert had worked on several large scale productions, he was hired by the film's producers as a consultant and oversaw filming.
The film takes place in 2017.
Filmed at Warner Brothers Movie World in Queensland, Australia.