The contents of the stash in the cargo plane comprised a shipment of gold war medals, Christmas mail correspondence, a crate of 100 bottles of Kentucky-made Old Crow bourbon whiskey, 1000 gold-bars in gold bullion and the entire payroll in cash for the American South Pacific Fleet. The value of the cargo in the film's story-line was said to be US $50 million.
The film was re-titled 'Treasure of the Yankee Zephyr' for its distribution in the USA. According to Allmovie, "Treasure of the Yankee Zephyr (1981) was first shown in America via pay-cable, where it carried no rating but was preceded with a warning vis-a-vis violence and strong language".
The make and model of the "The Yankee Zephyr" airplane was a US Navy DC-3 cargo plane - Dakota NZ3518. "The Yankee Zephyr" was played by an actual real-life DC-3 plane. It was repainted in United States Army Air Forces (AAF / USAAF) colors for the film and then sunk in Lake Wakitipu near Queenstown in the South Island of New Zealand. The plane was then raised from the lake after principal photography was completed. According to the forum on the 'Wings Over New Zealand Aviation' website, the plane was moored at Kelvin Peninsular in Lake Wakatipu for several months after production on the movie was finished. It was floating for a time about 100 meters off the shore under rafts of 44-gallon drums under its wings and fuselage. Jet boaters would jet-ski over the planes wings for fun. The plane was eventually scuttled, scrapped and finally sold but its ZK-BEU cockpit was salvaged and saved.
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.
The picture became a co-production between the countries of New Zealand and Australia after having originally been just a production of the country of the latter. Because of the joint venture between Hemdale and producer John Barnett's Auckland based Endeavour Films, a number of Kiwi actors and technicians got to work on the film, which involved the casting of New Zealand resident actors Grant Tilly and Bruno Lawrence'.
According to Helen Martin in the book 'New Zealand Film 1912-1996', the movie was "made with U.S. cinema audiences in mind . . . [and] . . . helped establish New Zealand's reputation as an excellent film-making location".
The American DC-3 military cargo plane seen in the movie was discovered by production designer Bernard Hides. The aircraft was originally manufactured in Oklahoma City in Oklahoma, USA during the 1940s. She first served with the Royal New Zealand Air Force (RNZAF) after which she was used as a training plane, a commercial carrier and finally as a 'stagliner' transporter carrying live deer across New Zealand.
Before the picture's setting was located to the South Island of New Zealand due to union disputes, the film was originally intended to be set in the rainforests of tropical north Queensland, Australia, specifically in the region of Cape York. This place, the official most northern locale in Australia, was originally considered as the main location, but had the film shot in Queensland, it wouldn't have necessary lensed there, due to its remote location, as there were more suitable Queensland locations with the same appropiate vegetation better suited for movie production.
Original director Richard Franklin was a lot more involved with regular collaborator Everett De Roche on the early drafts of writing the film's script than he had been on their previous collaboration Patrick (1978).
One of two 1981 movies directed by David Hemmings first released in that year. The other picture was The Survivor (1981). Both films were made with producer Antony I. Ginnane and both movies featured an airplane as a central story element.
Some of the movie's title-logos featured a blue-and-white star positioned between the words "Yankee" and "Zephyr" evoking an American star from the US flag which is known well to feature stars and stripes.
The picture has had three "Yankee Zephyr" titles. They are: "Race to the Yankee Zephyr" (its working and pre-release title), "Race for the Yankee Zephyr" (its main title) and "Treasure of the Yankee Zephyr" (its US title). In Australia, the film was promoted under "Race To..." just months before its theatrical release with a title-change to "Race For...". According to Scott Murray in the book 'Australian Film 1978-1994', some press books for the film gave the movie's title as 'Race to the Yankee Zephyr' (despite the film's title change) which "led many film writers to adopt that incorrect title".
The film was made in New Zealand instead of Australia due to an Australian Actor's Equity dispute. This was due to the refusal to permit four foreign actors (Ken Wahl (American), Lesley Ann Warren (American), Donald Pleasence (British) and George Peppard (American)) to be cast in the film's four top-billed lead roles, as such, this meant there would be not one Australian actor in any of these parts. Producer Antony I. Ginnane took the production to New Zealand and because of the move, the film's original director, Richard Franklin, who regularly worked with the film's scriptwriter Everett De Roche, left the film.
Second of two pictures first released in consecutive years starring actor Ken Wahl which featured a World War II era cargo plane. In this 1981 film the aircraft was a US Navy DC-3 (Dakota NZ3518) cargo plane whereas in the previous year's Running Scared (1980) it was a C-47 (or Douglas C-47 Skytrain) cargo plane.
The trivia item below may give away important plot points.
The film's closing epilogue states: "Barney and Sally Whittaker currently operate HELIJET TOURS in Queenstown, New Zealand. Gilbert "Gibbie" Gibson purchased and now runs THE DONKEY CLUB in Port Said".