The Aircraft in the movie is a B-24 Liberator and not a B-17 Flying Fortress. The B-17 was the first long range heavy bomber used by the U.S.A.A.F. The B-24 could carry a heavier bomb load. The B-24 could fly longer range than the B-17, which is was designed to augment in the arsenal of air power. The rear gun position did not look as in the movie, but was probably used to allow the viewer to see Burgess Meredith. The top turret shown in the film was never used on the B-24 or the B-17. That turret would have been found on the Martin bomber of the 30s and not used afterwards. In several shots they also showed Lockheed Hudsons as the bomber being flown. Hudsons were used greatly by the Brits, especially in their "moonlight squadron" operations. Agents were flown in Hudsons to occupied territory in the Hudson, although this was not the only use for the Hudson. A multitude of craft were used to parachute them.