Corrected entry: After the Lieutenant Commander lectures Lieutenant Tyler aboard the SS-33 about him not being ready to become a captain, the lieutenant leaves the room. As he closes the door a double vertical bar rank insignia can be seen on each side of his collar. The double bar is captain insignia in every branch of the military and in police departments nationwide. Lieutenant Tyler should be wearing single vertical bar insignia instead.
Corrected entry: In the film U-751 the torpedoes were shown leaving a trail of bubbles behind them. The type of torpedo which did that was the G7a 'T1' torpedo - which was pre-war issue. At the time of the film the standard torpedo of the Ubootwaffe was the improved G7e 'T2' torpedo which did not leave a trail of bubbles due to a different motor design.
Corrected entry: German torpedoes had two types of detonators. The primary was a magnetic pistol which was triggered by the presence of a large metallic object like a ship or submarine. The second was through mechanical 'feelers' in the event that the pistol failed and the torpedo contacted the target ship. Thus, the grazing 'miss' where the German torpedo scrapes along the hull of the U-571 could not have happened. The torpedo would have detonated.
Corrected entry: An additional torpedo-related mistake: U-boat torpedoes were launched with a ram, which pushed the fish out of the tube. The motor of an armed torpedo did not start until after the fish had left the tube. They were not propelled out of the tube by their own motors as shown in the film.
Corrected entry: W.W.II subs didn't have sub to sub attack capabilities and no underwater sub to sub kills were ever recorded during W.W.II.
Corrected entry: During the party at the beginning, Lieutenant Tyler addresses M. Dahlgren as "Captain." However, Dahlgren is wearing US Navy Lieutenant-Commander shoulder insignia, which is two ranks below captain. Tyler however, is wearing the right insignia. (00:10:30)
Corrected entry: At the end of the film, when the torpedo hits the German destroyer, the explosion is totally out of proportion. No matter how strategic the position it hit, no torpedo of that era would be powerful enough to cause an entire ship to explode. (It's true that this did occasionally happen to tankers, but that was due to the large amounts of oil being carried - not the case with a destroyer.)
Corrected entry: The scene where the German commander orders the survivors in the lifeboat to be shot is based on an allied myth. It is well documented that U-boat crews treated survivors gallantly - even giving them medical help, provisions, cigarettes and bearings to land. LATE (after the time this film supposedly takes place) in the war, Grossadmiral Karl Donitz even placed his own life on the line when he refused an order directly from Hitler that U-boat crews should execute survivors. He won on that issue and the order was rescinded, with only the comment that he should at least order his crews to STOP rendering assistance to the survivors.
Corrected entry: In the scene where the torpedo is running in the tube of the U-571 and could not be launched, reference was made to getting the fish launched before it detonated. That could not have happened. While it is true that the torpedoes did have a 'counter' of sorts to ensure a certain number or prop revolutions (distance) before the warhead would arm, that system was subordinate to another safety in the form of a 'tube feeler' which would not allow the counter to begin until the torpedo had actually cleared the tube. There was never any danger that the torpedo would detonate in the tube. The worst thing that could have happened was the fish would exhaust its fuel and be rendered useless.
Corrected entry: In reality the U-boat would never have been left without anyone on board capable of making repairs to critical systems like the diesel engines. Everyone on a U-boat crew had extensive training regarding all critical systems as well as access to a full set of blueprints that were carried on-board for just such events. Also, as U-boat crews worked in shifts, half of the engine room crew would be resting in the crew quarters when the fire broke out.
Corrected entry: In the scene where they took the Germans captive after assaulting the U-Boat, the black cook tells one of the Nazi's, "I bet you never seen a black man before, have you." At this time of history, the term "black" was never used, even by blacks themselves. They called themselves "negroes" or "colored".
Corrected entry: In this film it is the Americans who capture the enigma coding machine. However, in WWII it was a British submarine crew who eventually captured the device.
Corrected entry: When the U-571 is being depth charged one of the men asks Chief if he has ever been depth charged before. He says "once, in World War I..." But during WWII they did not refer to the first world war as World War I. They still called it The Great War. It wasn't until after WWII that either war was referred to that way. (01:18:10)