Continuity mistake: Doc Riedenschneider calls on Cobby in a dark hallway with brick walls and a door in the end with a half-open transom. Through this door, in the adjacent room, there are several gangsters seated a table. They go down the hallway and enter this room. In the next scene they have entered and the seated gangsters are suddenly no longer there. Nor is there a transom over the door. The hallway viewed from this room has white walls now instead of brick.
Visible crew/equipment: When Joe Gillis returns to the mansion, after Betty Schaefer has just revealed her love towards him, when he enters his room, you can see a hand wearing a watch in the mirror. (01:26:50)
Other mistake: A glass is dropped which had drink and one ice cube in it, however two ice cubes are picked up from the spillage.
Factual error: Between Earth and the Moon the crew of the spacecraft have an EVA in which they walk on the ship's metal hull with magnetic boots. At one point an astronaut inadvertently slips both boots off the hull and drifts off into space, helpless. There is a long shot of him drifting away in which his body spontaneously spins around 180 degrees and then stops rotating, which is all a violation of conserved angular momentum.
Visible crew/equipment: You can see Dean Stockwell's harness and guide wire when Kim is hauled off the ledge and up the cliffside.
Continuity mistake: Veta and her daughter are getting out the tablecloth. The daughter mentions Harvey's name and Veta shushes her. Cut back to the table being visible. In seconds, the tablecloth goes from barely unfolded to neatly spread out and straight.
Revealing mistake: In this scene we see Claudette Colbert and her husband talking. In the background it's obvious the ocean scene is a stage prop, the waves in the sea don't move at all.
Visible crew/equipment: During the dance scene, in the ladies room the shadow of the boom mic is seen in the mirror's reflection behind Ann. (01:10:00)
Revealing mistake: When there's a cave-in in the tunnel the POWs are building, you can hear, as the POW is tunnelling out of the cave-in, his trowel hitting the glass that separates him from the camera and crew.
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)
Plot hole: When major Singleton challenges Brant Royle to a duel with single shot pitons, he fires one pistol, and leaves the other pistol on the bar. He then goes into his carriage and shoots himself. He only has the pistol that has already been fired.