John Saxon, strictly adhering to Screen Actors Guild rules, refused to act in any scenes shot in America (all his scenes were shot in Italy) because this was not a union film. He credits SAG with saving his life, as he would have likely been on the helicopter that crashed, claiming the life of his co-star Claudio Cassinelli. He has not violated any SAG guidelines since. Two different but identically painted Bell helicopters were used for filming: the aircraft seen in close-up shots with Saxon has Italian registration, whereas the one seen flying--the helicopter involved in the fatal crash--has American registration.
Co-star Claudio Cassinelli died in a helicopter crash on July 12, 1985, during filming in Arizona. According to the National Transportation Safety Board report, the rotor blades of the Bell 206-B struck the underside of a steel bridge and broke off, causing the aircraft to plummet into the canyon below, killing Cassinelli and the pilot. The crash was officially attributed to inattention and poor judgment by the pilot. The NTSB report notes that a bottle of the prescription diet pill Ionamin (phentermine) was found in the pilot's hotel room, and that this drug may cause errors in judgment, but his actual use of the drug could not be verified because his body was never recovered.
The Terminator (1984) was Sergio Martino's influence for the film.
The futuristic shotguns shown prominently in most of the gunfight scenes, is the Franchi SPAS-12, of Italian origin. Its one of the most futuristic and popular 12-gauge combat shotguns of its time.