Factual error: When Roberts makes a deal with the Captain, he demands that the Captain grant liberty to both sections (i.e., the entire crew), leaving only Roberts and one enlisted man aboard as the deck watch. All U.S. Navy ships must have enough personnel aboard at all times to get the ship underway immediately, if necessary, which is why the crew is divided into watch sections.
Factual error: The movie takes place around the time of WWI, definitely before 1923. In the carnival scene, the calliope is heard playing "Ain't She Sweet". This was the number one song ... in 1927.
Factual error: When they are driving in the convertible, before the tarantula attacks them with the stones, if you look at their hair, it's not moving with the wind. If they were driving a convertible that fast in real life, it would.
Factual error: While the Confederate captain is explaining the mission, a couple of the "patriots" are inserting cartridges into their Colt Peacemakers. A neat trick, since the Civil War ended in 1865, and the Peacemaker wasn't introduced until 1873.
Factual error: After Harry Powell disappears from in front of Ms. Cooper's yard, a barn owl swoops down on a rabbit. We can hear the owl's wings flap even though barn owls make no noise when they fly.
Factual error: When Jimmy Stewart is almost down to the runway during the bad weather, the aircraft exterior shots show the type of cloud tops found only at high altitude, not low to the ground.
Factual error: When Hawkins prepares to leave Princess Gwendolin's chamber, a pet cockatoo sits on a pole near the window. Now how could a parrot native to Australia - or even a "papagei" from South America, as Hawkins intones - appear in medieval England when neither continent would be discovered for several centuries?
Suggested correction: Birds, of course, range widely and flexibly, a storm in the 1800's introduced small African storks to the Americas, Australian birds, to a degree, can be found in Tropical Asia, and therefore could have found their way to Europe via the exotic animal trade (which did well enough for the wealthy at the time),, and the word papagei? Medieval information, and word origins are notoriously fuzzy, ie the first animal to ever be called "penguin" was a similar Northern Hemisphere creature called the Great Auk.
Factual error: The opening scene shows Spencer Tracy on a crack streamliner in the desert east of Los Angeles, featuring red and orange coaches. Such equipment was used by the railroad on only two trains, neither of which crossed the desert east of Los Angeles, and both of which had matching red and orange locomotives. In the film the train is pulled by a dark gray locomotive normally used only to haul freight, and in a close-up shot the number in the locomotive is preceded by an X, which in the language of railroading refers to an extra train.
Factual error: When Dick has fallen into the hole in the swamp and is shooting at alligators, he manages to fire eight shots from a six-shot revolver.
Factual error: Near the beginning of the film, there is a reference to Capt. Merriwether Lewis being summoned to the "White House." That scene takes place in 1804. In reality, the Executive Mansion was not called the White House until 1811.
Factual error: The system devised to get the height right was, in the film, said to have been thought of by the 617 Sqn crews following a visit to the theater. In reality it was devised by the 'boffins' at Farnborough.
Suggested correction: See many previously posted 'mistakes' of this type and the standard correction: this is not a documentary and never pretended to be. It is a war drama and many facts were changed to fit the action.
Those correction are often made in fallacy. Dramas based on historical accounts have liberty to change small or inconsequential things, like adding a person that may have never existed, or change a relationship for dramatic purposes. Despite not being a documentary, unless it's a fantasy film, changes in historical facts are mistakes (for example, a drama can't have the Eiffel Tower in London just because it's not a documentary).
Suggested correction: This was the version given in Brickhill's book. The real story wasn't published till many years after the film was made.
Factual error: Towards the end of the film, the German troops are searching for the marines and cross from the dockside to lighters and then on to a harbour launch. Although this is supposed to be in Bordeaux the launch is marked 'PLA' or Port of London Authority where the action must have been shot.
Factual error: The Boccherini string quintet is actually scored for 2 violins, 1 viola and 2 cellos, not the crooks' line-up of 2 violins, 2 violas and 1 cello.
Suggested correction: I don't really know anything about how string quintets (or quartets) perform, or how any group of musicians might prepare to perform a well-known piece composed many years ago. So maybe my answer is not valid. But would it be acceptable within the music community for a musical group to re-score a piece, so long as they remain faithful to the original? If two members of a string quintet said they were more confident and capable on a viola than on a cello, would the quintet re-score the piece accordingly? Is it acceptable for musicians to adjust a long-established piece of music? Another possibility. The crooks are not musicians at all. They pretend to be musicians, but this is only a "front" for a bank robbery they are planning. They maintain the pretence by miming to records. So is this a subtle joke?"Look, the crooks are pretending to be musicians, but they are getting it all wrong! They are playing the wrong combination of instruments. Ha ha!"
I asked a friend who belongs to a string quartet if you could re-score a quintet piece. She said this would be complicated, difficult, and more trouble than it was worth. So I must retract my suggestion that the crooks re-scored the Boccherini String Quintet. But maybe I am right with my other suggestion. The crooks are not musicians, but only mime to records. Thus, they use the wrong combination of instruments. This is therefore intended as a subtle joke.
Factual error: The tank the creature's in has sharks and barracudas, salt water sea creatures, when he's said to be of fresh water origin.
Factual error: All the troops in the Fetterman massacre are cavalry. In fact, the majority of the detachment, including Fetterman himself, were infantry.
Factual error: When Kitchener is shown inspecting Harry's old regiment, one group of African or Egyptian troops is shown to be wearing the Pattern 1914 Infantry Equipment, not made until 1914 at the earliest. Additionally, it has the 1918 modification to have two closing straps, so is over 20 years too late for the 1894 date at that point.
Factual error: The landscape shows late fall, with color and fading leaves. But on the bushes near the killer porch when Captain arrives for muffins are full of spring bloom Azaleas.
Factual error: At the end of the movie, Lady has four puppies, three Spaniels, like her, and one mixed breed, like Tramp. Realistically, they would all be mixed breed with characteristics from both parents.