Warren Beatty turned down the role of Rickson, possibly because he had recently caused the divorce between Natalie Wood and Robert Wagner, and the two men were not on speaking terms.
Mike Reilly drowned after parachuting from 2000 feet into the English Channel, near Newhaven, during the filming of a stunt for the film. He was 29 years old, had more than 300 jumps, was British parachute champion and the first Chairman of the newly formed British Parachute Association.
Steve McQueen had a stand up row with wardrobe mistress Wyn Keely after a blouse worn by Shirley Anne Field didn't rip during their kissing scene on the first take.
Three Boeing B-17 Flying Fortresses, restored to flying condition in World War II configurations, were used during filming. Clever camera work and multiple shots of the planes with different names painted on their noses were mixed with wartime footage to create the illusion of an entire Group of B-17 bombers. Noted aviation author and pilot Martin Caidin, who helped fly one of the B-17s from America to England, chronicled the restorations of the aircraft, their flight across the Atlantic, and their use in the film in his book "Everything But The Flak."
This film used three B-17's in the production of this film. Over fifty years after this film was made, there are only twelve B-17's in the world that are airworthy. There are thirty-three additional B-17's that are either on display in museums, restored and in storage or are being restored.