Revealing mistake: When the boat is supposedly surrounded by a swarm of flies, they're really just relatively few flies trapped between two panes of glass in front of the camera lens. Evidence: whenever the camera moves, the "swarm" moves with it against the background, and you can even see some of the insects walking on the surface of the glass.
Continuity mistake: Alice Tripp is wearing different shoes when she starts walking home from the movie with George Eastman than she is when they are close to where she lives.
Continuity mistake: When the giant is fighting the bull, in the long shots the bulls horns are white, but in the closeups, they're black.
Continuity mistake: During the final dance number, Vera-Ellen's skirt alternates repeatedly between long and flowing and short and tight - perhaps to facilitate some of the dance moves.
Continuity mistake: Near the end of the film, Karl Malden is embracing Vivien Leigh. In one shot she has her left forearm against his chest, with her hand in the vicinity of his shoulder. In the next shot this arm is instantly around his neck.
Continuity mistake: When Jerry gets in Milo's car so that she can get cash to pay him for his paintings, they get into a dark green car. In the next shot they get out of a light (slightly greenish) blue car. (00:23:00)
Factual error: Sargent Nevins (Arthur Kennedy) is shown playing a pinball machine in the military rec room. When the camera turns to the play field of the machine, it is clear that this machine has flippers, and flipper buttons are visible on the side of the body. The movie takes place in 1943, but flippers didn't appear on pinball machines until 1947. (First machine to have flippers was Gottlieb's 'Humpty Dumpty.'. (00:37:30)
Continuity mistake: After the first training montage, Alice is worried she might have flunked Meteorology and asks Marcie a question. When the door opens and everyone laughs, they both are in wildly different position than in the previous shot. (00:09:05)