Continuity mistake: When the butler tells of Harry Lime's death, at the start of the conversation he can hardly speak English. As the conversation goes on, his English gets better and better, until at the end it's perfect with just an accent.
Suggested correction: He is reluctant to speak English at the start possibly to avoid trouble but later decides otherwise.
Revealing mistake: When a car drives by a store front and two hand grenades are thrown at it, the hand grenades bounce back into the street before the store blows up.
Continuity mistake: When Leona picks up her hand mirror, her medicine tray is positioned directly in front of her on her bed. When she puts the hand mirror down in the next shot, the medicine tray is pushed about a foot away from her bed.
Revealing mistake: When Ballin's plane flies and finally crashes, it becomes obvious that the horizon is a still image with the film of the explosion superimposed directly onto it.
Continuity mistake: Pinkie sweeps all the glasses on top of the bar onto the floor, yet after he and his gang have gone we see broken glass on the bar top.
Continuity mistake: The dead body Wally discovers in the house has its head straight in the long shots, but canted to the right in the close ups.
Visible crew/equipment: Towards the end of the fairground scene, as Michael and Ellen are walking to the right, and just before the cop tells them one of the stolen bills has been passed to the dress shop, the shadow of the boom microphone is visible across the brick wall in the background. (00:22:20)
Revealing mistake: When Joan Crawford shoots van Heflin, he reacts as if he was shot before the shot is fired.
Continuity mistake: When Quinlan is with Joe Grandi at the bar, Quinlan breaks his sobriety while seated at a round table, but in the last overhead shot the table is rectangular. (00:57:00 - 00:58:25)
Continuity mistake: Dick Powell puts his gun in his left trenchcoat pocket and then 2 minutes later takes the same gun out of his right pocket.
Plot hole: Early in the movie, when Joe Stefanos tells Mary, the owner of the luncheonette, that he found Jeff Bailey by passing by and seeing the name on the sign of the gas station, it makes no sense. He only knew him by the name Jeff Markham. Even if he was just lying to her, he uses the same explanation when he is alone talking to Jeff. We never know how he found him.
Suggested correction: He told Jeff that he saw him pumping gas at the station.
Continuity mistake: The protagonist wakes up screaming and runs away from her cabin. A conductor restrains her. During the scene, the shadows on the wall/poster and on the torso of the black helper heavily change depending on the camera angle used. (00:02:25)
Continuity mistake: When the stunt person for character Mrs. Kraft rolls horizontally down the dune, the stunt person's head is pointed west, but the scene picks up with the character's head pointed east. (01:10:00 - 01:13:00)
Continuity mistake: The Cadillac limo changes models at times, also having blackwall or whitewall tires.
Continuity mistake: Johnnie, Lina and Beaky are playing anagrams. Lina spells out the word MURDER with an M as the first letter. The shot cuts away and then back again, and now the first letter is an inverted W. (01:01:40)
Revealing mistake: Several pieces of furniture, including a large sofa, fall over before the suitcase bomb actually explodes.
Other mistake: Holmes appears disguised as a Sikh, complete with turban and beard. Although his face is black, his hands are without any make up and are white as snow.
Continuity mistake: When Robert Taylor escapes from the asylum, and is driving the second car he steals, the car is shown at least once with windshield wipers pivoting from above the windshield, then shown with the wipers pivoting from below the windshield. Clearly, these are two different cars. I think the studio borrowed wiper footage from the scene in which he is driving the first stolen car, to use at moments in the scene in which he is driving in the second car.
Continuity mistake: Dr. Luther Brooks is in the changing room with Dr. Dan Wharton. During their conversation, one of the lockers behind Brooks' is open, its door quite close to him. In the close-ups though, all the lockers are closed. The shadows are also different. (00:04:00 - 00:04:40)