Andrew Davis was attached to direct the picture based on a different screenplay. The budget being too high and creative differences arising, Carolco hired Roland Emmerich, fresh from his low budget feature Moon 44 (1990) and a canceled Sylvester Stallone vehicle "Isobar", to deliver a new screenplay and direct the film.
The production script presented a much darker depiction of the U.S. Military than what eventually ends up on the screen. In the screenplay the Colonel in charge of the Unisol project orders Dolph Lundgren's character to ruthlessly kill off all the civilian witnesses to his pursuit of Jean-Claude Van Damme's character. The Colonel also informs the head scientist that the terrorists at the dam were not terrorists at all, but mercenaries hired by the army to provide fake justification for the Universal Soldier program. In the finished film, these scenes are omitted so the witnesses are left unharmed and the gunmen killed by the Unisols at the dam were genuine terrorists. The Colonel and his men are actually heroic figures with a real and valid mission who just want their multi-million dollar Unisol back. Whereas military villains were de rigeur in the post Vietnam 1970s and well into the 80s, by the time of filming the reputation of the U.S. Military was at an all time high following the first Gulf War so it was considered unlikely that the audience would accept them being shown in such a poor light.
The last film to be recorded in CDS, an early digital sound format. In the following year of the film's release, sound technicians had developed DTS. This sound format was apparently of higher audio quality than CDS and has been used in most movie theaters ever since.
The Grand Canyon bus chase was re-edited years later as library footage into Fred Olen Ray's Critical Mass (2001) produced by Andrew Stevens' Phoenician Entertainment (a company that specialized in shooting low budget action films around stock footage).
(at around 8 mins) Only feature film as of 2012 depicting an Aero Spacelines Mini Guppy (Registration N422AU, serial 15937) transport aircraft. The Mini Guppy used in the film was used by Erickson Air Crane until its retirement in 1995 at the Tillamook Naval Air Station Museum in Tillamook, Oregon.
The house scene was actually built at the Peck's Lake golf course in Clarkdale, Arizona. Nearby was the Clark Mansion which was built for one of Senator William Clarke's sons who died in a plane crash nearby in 1932. The mansion burned down under mysterious circumstances in June 2010.
The trivia items below may give away important plot points.
In the film's unreleased first cut, the final battle between Luc and Andrew didn't include the scene in the barn, which was shot months later after the first test-screenings, featured the death of Luc's mother, and concluded with the near-murder of Luc by Dr. Gregor, followed by the revelation that he eventually died because of his injuries.
The movie has some unusual resemblance to Italian 1986 Terminator-sploitation movie Hands of Steel (1986), in which a soldier turned cyborg assassin regains some of his memories, evades his masters and falls for a woman who helps him.