Though the film was set in Russia, authentic filming locations were not possible due to the Cold War, forcing Eastwood's and Fritz Manes's Malpaso Company to rely on Vienna and other locations in Austria to double for many of the Eurasian story locations. The film was shot on a $21 million budget, the largest production budget ever for Malpaso. Of that amount, over $20 million was spent on special effects.
A joint Anglo-American plot is devised to steal a highly advanced Soviet fighter aircraft (MiG-31, NATO code name "Firefox") which is capable of Mach 6, is invisible to radar, and carries weapons controlled by thought. Former United States Air Force Major Mitchell Gant (Clint Eastwood), a Vietnam veteran and former POW, infiltrates the Soviet Union, aided by his ability to speak Russian (due to his having had a Russian mother) and a network of Jewish dissidents and sympathizers, three of whom are key scientists working on the fighter itself. His goal is to steal the Firefox and fly it back to friendly territory for analysis.
However, the KGB has got wind of the operation and is already hot on Gant's tail. It is only through the sympathizers that Gant remains one step ahead of the KGB and reaches the air base at Bilyarsk, where the Firefox prototype is under heavy guard. The dissident scientists working on the Firefox help Gant infiltrate the base. Dr. Pyotr Baranovich (Nigel Hawthorne), one of the scientists, informs Gant that there is a second prototype in the hangar that must be destroyed. The diversion will allow Gant to enter the hangar and escape with the first Firefox. Gant knocks out Lt. Colonel Yuri Voskov (Kai Wulff), a Soviet pilot assigned to take the first prototype on its maiden flight during a visit from the Soviet First Secretary. The scientists attempt the destruction of the second prototype to give Gant time to suit up and start the first fighter, but the second prototype is not destroyed, and the scientists are killed by the guards. Fortunately for Gant, he escapes the hangar and lifts off just as the First Secretary arrives.
Evading the Soviets' attempts to stop him, Gant barely reaches the Arctic ice pack and lands for refueling, making a rendezvous with a US submarine whose crew refuels and rearms the aircraft. However, Gant's last-minute refusal to kill Voskov has consequences; the Soviet pilot flies the second prototype, with orders to wait for him at the North Cape area. Gant completes the rendezvous and is on the way home when Voskov engages him in a dogfight. After a long battle, Gant barely manages to fire one of his rearward missiles and Voskov's plane is destroyed. Satisfied that there are no other Soviet forces chasing him, Gant begins his flight to safety.Clint Eastwood as Major Mitchell Gant
Freddie Jones as Kenneth Aubrey
David Huffman as Buckholz
Warren Clarke as Pavel Upenskoy
Ronald Lacey as Dr. Maxim Ilich Semelovsky
Kenneth Colley as Col. Kontarsky
Klaus Löwitsch as Gen. Vladimirov
Nigel Hawthorne as Dr. Pyotr Baranovich
Hugh Fraser as Chief Inspector Tortyev
Stefan Schnabel as Leonid Brezhnev
Thomas Hill as General Brown
Clive Merrison as Major Lanyev
Kai Wulff as Lt. Col. Yuri Voskov
Dimitra Arliss as Natalia Baranovich
Austin Willis as Walters
Michael Currie as Captain Seerbacker
Alan Tilvern as Air Marshal Kutuzov
John Ratzenberger as Chief Peck
Wolf Kahler as KGB Chairman Yuri Andropov
The film was based on the creation of a "mythical" super fighter: the MiG-31 Firefox. The original Firefox from the novel was, cosmetically, nearly identical to the MiG-25. The more intimidating version seen in the movie was created specifically for the film, and takes many of its design cues from the North American XB-70 Valkyrie. In the sequel novel, Firefox Down!, the Firefox's appearance is described as matching the one in the film. For filming, four large-scale replicas were created, along with one full-size model that had dimensions of 66 feet long, 44 feet wide, and 20 feet high. The full-size model was built from a radio station broadcast-antenna skeleton and was capable of taxiing at 30–40 mph.
Filming occurred in 1981 at a number of locations including Vienna, Austria; Montana; California; London and Greenland's Thule Air Force Base. Hollywood aerial cinematographer Clay Lacy flew second unit aerial sequences in a Learjet 23 high-speed aerial platform, for scenes that were later integrated into the film.
Special effects supervisor John Dykstra pioneered a new technique for shooting the complex flying sequences, called reverse blue-screen photography. This involved coating the model with phosphorus paint and photographing it first with strong lighting against a black background and then with ultraviolet light to create the necessary male and female mattes to separate the foreground model and the background footage. This enabled the shiny black model to be photographed flying against a clear blue sky and gleaming white snow; compare this with traditional bluescreen technique used in The Empire Strikes Back. The original scale model made by Gregory Jein used in the bluescreen work is now on display at the Warner Bros. Museum.
Author Howard Hughes gave Firefox a negative review, "Watch the trailer, read the book, play the game — just avoid the film, it's another Eiger Sanction. Less a 'Firefox', it's more of a damp squib, or at best a smoldering turkey." Vincent Canby's review in The New York Times made a similar assessment, zeroing in on Eastwood's lack of control over the plot line. "Firefox is only slightly more suspenseful than it is plausible. It's a James Bond movie without girls, a Superman movie without a sense of humor." However, Roger Ebert gave the film a positive review, describing it as "A slick, muscular thriller that combines espionage with science fiction. The movie works like a well-crafted machine."
Review aggregation website Rotten Tomatoes gives the film a score of 42% based on reviews from 11 critics.