Continuity mistake: In the scene where Trevor Howard and José Ferrer are sharing what appears to be some port (about 50 minutes into the movie), the port decanter has a drip stopper in the long shot which disappears in the close-up shot of Leslie Howard and then re-appears in the following longer shot.
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.
Other mistake: While all the business signs in downtown Osaka are properly in Japanese, the local newspaper, The Osaka Times, is printed entirely in English.
Continuity mistake: When the bogus male nurse with Mrs. Carroon is outside in the rain, his coat and hair are soaking wet. But when they run to the staff entrance (a few seconds later), his hair and coat are bone dry.
Continuity mistake: When Tom is running away from Uncle Pecos, he runs into the house and slams the door. When he slams the door, you can see the little door at the top has nothing on it, but in the next shot a handle has suddenly appeared.
Character mistake: After Cal goes to the secret lab in Georgia, he and two others go into his new lab. When they enter a cat jumps up on the counter. Dr. Adams says "This is Neutron. We named him that because he's so positive." Neutrons are neutral and electrons are negative. It's protons that are positive. They should have named the cat Proton.
Continuity mistake: When Tom finishes drawing up the blueprint, he draws a mouse and writes the word "Mouse" underneath it. When the blueprint comes to life after Tom lies down on the bed, the word "Mouse" is now underlined.
Visible crew/equipment: When Joseph, Albert, and Jules trip over the sewing mannequin, Felix mistakes it for his wife. Then, Joseph walks back over to the desk, and the actor's tape mark is visible on the rug near Felix's feet.
Deliberate mistake: Glenn Ford strikes the window in the library door with his briefcase and it instantly shatters. In reality, a blow delivered by a briefcase to a plate glass window would have produced no more than a scratch or crack.
Continuity mistake: When Calvin Q. Calculus has invented the portable hole, he says "Eureka!" and you can that there is a beaker on the desk, but in the next shot the beaker has disappeared.
Continuity mistake: When Sam closes the door after escaping the lions, you can see there is nothing under his feet, but in the next shot a doormat has suddenly appeared.
Revealing mistake: Near the end of the film, when Tony "Stephanois" caresses Jo's hair, his right eye twitches, although he is dead. (01:05:54)
Continuity mistake: When Manuel takes off his sombrero to give to the other mice, you can see he has a straw in his hand, but when we see Manuel in the next shot, the straw is nowhere to be seen.
Revealing mistake: Air can be seen coming out of the creature's head at one point in one of the tank scenes.
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.
Revealing mistake: Several shots and whole scenes throughout this film are flipped horizontally in such a blatant fashion that even the name of the ship, "Sans Souci," appears as a mirror image.
Continuity mistake: When we first see the book that Bugs is reading at the beginning of the cartoon, there are words on the front cover and spine. In the next shot, the words have gone.
Continuity mistake: When Hippety Hopper breaks his crate apart on the rocks, you can see there are pieces of crate on the ground, but when we see Hippety in the next shot, the pieces have disappeared.
Continuity mistake: When Jervis returns Julie to her suite after a night of dancing, he picks up a morning paper, reads some excerpts from it, then says goodnight to her. As she opens the door, all he has in his hands is his boater, no newspaper, and in the following long shot, no paper is visible anywhere.
Continuity mistake: When the camera pans in on the audience at the start of the show, you can see that Granny is sitting next to Bugs and Daffy, but after a quick cut to Elmer, we return to Bugs and Daffy, and Granny has disappeared.