This is a really minor Goof but hard to understand, considering that the Army Air Force co-operated heavily with production of the film.
The Boeing B-17C "Mary Ann's" serial number is 40-1104 (shortened for radio transmissions to 01104) but that aircraft actually was a Vultee BT-13 trainer, not a B-17.
Additionally, Winocki describes himself as a tail gunner when the B-17C did not have a tail position. That change was made in the E model and subsequent versions.
Partway through the film, a field modification is made to the Mary Ann by curring away the rearmost part of the fuselage to allow installation of a machine gun to protect the tail.
The Boeing B-17C "Mary Ann's" serial number is 40-1104 (shortened for radio transmissions to 01104) but that aircraft actually was a Vultee BT-13 trainer, not a B-17.
Additionally, Winocki describes himself as a tail gunner when the B-17C did not have a tail position. That change was made in the E model and subsequent versions.
Partway through the film, a field modification is made to the Mary Ann by curring away the rearmost part of the fuselage to allow installation of a machine gun to protect the tail.