Trivia

This movie is based on a true to life incident about the disappearance during World War II of an American DC-3 military airplane which was carrying the payroll for the American Pacific Fleet and crashed but was later found off Cape York in North Queensland, Australia. Screenwriter Everett De Roche has said he conceived the film from this story, which had been told to him by one of his neighbors in Mount Isa in Queensland, Australia.

After David Hemmings fell behind schedule, Brian Trenchard-Smith was brought to New Zealand to serve as a potential second unit director. This implied threat of replacement bolstered Hemmings' resolve, and he managed to complete the remainder of filming on time. Trenchard-Smith and Hemmings would later work together on Turkey Shoot (1982), and the former would also use the nickname of a henchman in this film - "Mr. Broken Teeth" - for a character in his novel "Alice Through the Multiverse".

The film is dedicated jet-boat coordinator Colin Robinson and jet-boat drivers John Rillstone, Bill Clarke who were killed during the filming of the jet-boat sequences. The dedication included in the closing credits reads: ''This film is dedicated to John Rillstone and to Bill Clarke & Colin Robinson who lost their lives on the Kawarau River, Queenstown, whilst operating Jet Boats''.

The makes and models of the helicopters seen in the movie included an old Hughes 300 (269c) [the main chopper in the film] as well as a Hughes 500C, a Hughes 500D and a Bell 206 JetRanger III.

Because the film went over budget and schedule, Donald Pleasence had to withdraw from the role of Blair in John Carpenter's The Thing (1982).