Charles Bronson once said of his Albert Johnson character in this movie: "There are two schools of thought about the characters . . . Some believe the man [Albert Johnson] was a criminal. Others believe, as I do, that he was innocent of any wrongdoing. We decided to show him as a man who was a victim of someone else's need to perform violence. In trying to protect himself against an unprovoked attack, he was forced to kill one of his assailants."
The manhunt that this movie is based on was the first time that airplanes were used by authorities in Canada to track down a wanted fugitive. The type of plane used was a a Bristol open cockpit bi-plane and a real-life replica was constructed for this movie.
Based upon a true story, the film was heavily criticized by Canadian historians for getting many historical facts and characterizations wrong.
The pilot character of Capt. Hank Tucker of the Royal Canadian Air Force, played by Scott Hylands, was based on Capt. Wilfrid Reid "Wop" May, OBE, DFC, who was the real life pilot who assisted the manhunt with aerial surveillance.
When they appeared together in the box-office hit The Dirty Dozen (1967), Lee Marvin was the top-billed star and Charles Bronson was among the ensemble cast credited alphabetically and after Marvin. After Paint Your Wagon (1969), Marvin's career and star power declined considerably. Bronson received top billing for this film and Marvin received second billing. However, some theatrical posters have Marvin's name elevated in height above Bronson's, even though Bronson's appears first on the left and Marvin's second on the right.