Factual error: For a B-17 crew that has flown 24 missions, those on the Memphis Belle don't act very professional or experienced. Gunners that fall asleep and fight like schoolkids over lucky charms, navigators with hangovers, co-pilots that leave their posts to have a turn at the guns. If the real Belle crew had been like that, they would not have lasted that long.
Factual error: When Lt. Col Derringer (John Lithgow) is introducing the crew of the Belle at the beginning of the film, he describes Rascal as being 18 years old. Yet he holds the rank of Staff Sergeant (E-6), a rank usually achieved after at least 5-6 years of military service. Same can be said for Eugene, who is described as being 19 years old, who also is a Staff Sergeant.
Factual error: In the last minutes of the film, as Memphis Belle is coming in to land, you just catch a glimpse of a very big hangar. This is Hangar 1 at Duxford, the Imperial War Museum where a lot of the flight filming was based at, and was built in the 1980's. This hangar was rebuilt and enlarged and is now called Airspace.
Visible crew/equipment: During the take-off sequence, in a close-up showing a ground crewman pulling the chock away from the front of a tire, production crew and a van can be glimpsed in the far distance out of focus before being obscured by more period accurate vehicles and extras.