A Yank in the R.A.F.

Tyrone Power's flying stunt double in this movie, RAF pilot Lt. Harold Barlow, was shot down by German aircraft and taken prisoner, according to a 20th Century-Fox press release of 24 January 1942.

The original screenplay had the American lead character Tim Baker, played by Tyrone Power, die at the end of the movie during a German aircraft attack. According to notes from the Twentieth Century-Fox Produced Scripts Collection at the UCLA Arts-Special Collections Library, a 25 November 1940 conference stated "the serious objection to Ty [Tyrone Power] would be that audiences would resent his dying at the finish, and not getting the girl." Moreover, according to the book "The Films of World War II" by Joe Morella, Edward Z. Epstein and John Griggs, the British military establishment requested that the studio allow the character to live because "apparently they didn't want to give American moviegoers the impression that Americans helping Britain would die." Notes from the Script Collection report a further conference on 31 January 1941 that substantiates this by saying that Zanuck had had discussions, "unofficially with some British officials." English officialdom had felt that the lead character should not die, thereby not showing any more deaths than those that were absolutely essential to the movie's story. Further, a film with a major star like Power was also unlikely to have him killed at the end anyway, which also may have affected the box office. The original ending in which Baker was killed was actually filmed. On 18 August 1941, "The Hollywood Reporter" stated that Darryl F. Zanuck ordered a new ending to be filmed. A 13 September 1941 "Motion Picture Herald" article states "the happy ending [was] filmed after early preview audiences protested the killing of the hero at Dunkirk."

According to the book "Bill Collins Presents The Golden Years of Hollywood' by Bill Collins, "Some filming was done in America. The RAF Harvard trainer and the Hudson bomber were made in the United States for British contracts, so it was possible to get some fine footage at Lockheed's Burbank facility. As there were not Mk.1A Spitfires or German BF-109Es in America, Twentieth Century-Fox had one of each constructed at the studio in Los Angeles. In England, Ronald Neame and his team worked at the RAF's No. 602 Squadron ("City of Glasgow") to capture authentic shots of take-offs, aerial formations and so forth . . . the marvelous five-minute sequence at Dunkirk was actually achieved on the California coast at a cost of $100,000."

Camera operator Otto Kanturek and his uncredited assistant, aerial photographer Jack Parry, were both killed in a plane crash when a Hurricane fighter collided with their Avro Anson camera plane over Cawston, Norfolk, England, on 26 June 1941. Other reports state that, according to 20th Century-Fox publicity, the two men were flying to England to shoot fight sequences and after the footage was shot, the plane they were in was attacked and shot down by German aircraft.

The scenes with the Spitfires were filmed in the UK. The Spitfires were from 602 Squadron under the command of Squadron Leader Sandy Johnstone. The unit was resting in early 1941 in Scotland after fighting in the Battle of Britain.