The belly landing sequence was lifted from the film "Twelve O' Clock High" and was originally executed by Hollywood pilot Paul Mantz in June 1949 at the then-closed Ozark Army Airfield west of Dothan, Alabama, for a reported fee of $2,500. B-17 N17W was marked exactly as the bomber in the 1949 production, right down to the spurious serial number, to match the borrowed footage.
The low-level buzz job was done by Don Lykins, Bob Grider, and Ed Maloney in 44-83684. The shots, filmed on Wednesday, 17 January 1969, consisted of six very low passes made across the movie set and shot from four different camera angles. These were used in various parts of the film.
The code letters "DF A" seen on an aircraft in this film (e.g., 54:58) are the identification codes for the famous Memphis Belle, the subject of a widely acclaimed William Wyler film. Memphis Belle flew with the 91st Bomb Group. The makers of this film did a good job of copying the style of the letters, which was a nonstandard style.
The gunship concept was tested in 1943 with several modified B-17s, redesignated as the YB-40. The planes were extra ammo, and guns. However, the additional weight led to gunships unable to keep up with regular B-17s that had dropped their bombs. The project was scrapped
Only three B-17s were actually used to make the film: DB-17P 44-83684 (N3713G), DB-17P 44-83525 (N83525) and B-17F 42-29782 (N17W). N3713G, provided by Ed Maloney's Air Museum at Ontario, California, had been the primary aircraft used in the television series of "Twelve O' Clock High."