Factual error: During the war games they have Jefferson pose as a major in order to facilitate the commandeering of the ambulance and the jeep. Regardless of their personal feelings in the matter the ambulance crew and the driver and troops in the jeep would be perfectly aware that no black man would ever be promoted to a position of authority in an otherwise all white command. We may find it repugnant today but the US Army was rigidly segregated during World War 2 - and it stayed that way until 1948. Jefferson may have been inducted into a special unit like the Dirty Dozen but considering that the future of the entire mission is riding on their success at the games, throwing it all away like that makes no sense at all.
Factual error: The raid on the chateau takes place during the evening before the D-Day landings, in Rennes in Brittany, almost exactly halfway between Cherbourg and the Normandy beaches - both thought highly likely to be the site of the Allied landings. On the evening before the landings - the night of the raid - the area was heavily bombed by the RAF and dummy parachutists and radar-jamming devices were dropped into key areas, many close to Rennes itself. One dummy parachute drop succeeded in drawing an entire German infantry regiment away from its position just six miles from the Normandy landing beaches! The Germans knew something was happening and the landings were imminent - they just didn't know exactly where they would happen. Given all of this it is absurd to think that so many high ranking German officers would be enjoying themselves in a glorified brothel. They would be with their units preparing a counterattack, or at the very least on their way back.
Factual error: When Resiman interviews him in prison, Franko is chewing gum. (In several shots you see it is chewing gum and not tobacco). First, during heavy rationing in the UK in World War 2 chewing gum was a rare and expensive treat. A military prisoner would not be able to obtain it for love or money. Secondly, US military prisoners were never, ever allowed chewing gum - it can be (and has been) used to jam locks.
Factual error: The film opens with a US soldier being hanged, the lever is operated by a US Noncom. Wrong. The US forces were allowed to hang their own on British soil, but only if a British executioner was used. The executioner would have been our own Mr Pierrepoint.
Factual error: Col. Everett Dasher Breed is wearing Ray Ban Way Farer sunglasses. They were not designed until 1952.