Continuity mistake: After the Memphis Belle drops its bombs and scores a direct hit on its target you see the Memphis Belle lift up and turn right with the bomb bay doors closed. The next scene the bombadier says "okay, bomb bay doors, closing" and you see the doors close again.
Continuity mistake: When the bottom turret is shot out, Rascal is hauled into the aircraft, and although the turret is completely destroyed, when the Belle lands, the bottom turret is visible and intact again.
Continuity mistake: When the 3rd engine is going out, you see both of the landing gears are up, but it was just moments before that Dennis already lowered the left landing gear.
Continuity mistake: In one scene, Jack discovers the 'couldn't get laid last night' note Genie taped to his back, then a couple of scenes later, when Rascal is telling the crew the joke he heard from one of the waist gunners from Windy City, the note is taped to his back again.
Factual error: They hold a huge dance in the hangar at night, and Dennis leaves to walk to the Memphis Belle through the hangar doors, which are wide open. The whole flight line, tarmac and hangar are bathed with light - on a US Air Force base in East Anglia during the height of the German bombing offensive. Haven't they heard of the blackout? Why not just paint a big fluorescent sign on the runway saying 'Please Drop Bombs Here'?