Audio problem: In the boiler room, Blore responds to Lombard saying "I still wanna be a living idiot." In the next shot, Stanley Holloway's lips are moving with no sound before Shirley Eaton's arrival. (01:00:00)
Continuity mistake: Blore threatens Lombard with a monkey wrench he holds with his thumb pointed up along the metal bar in close-ups, or just wrapped around it in the other angle. (01:00:05)
Continuity mistake: Upstairs when Blore messes up the generator, the Judge and the Doctor are at a standoff with their matches. The doctor has a pool cue leaning against his shoulder in the front view, away from him in the reverse shot. (01:00:40)
Continuity mistake: Judge Cannon's magical handkerchief misbehaves right at the beginning of the dinner scene when he tries to make everyone else confess; it's not even in sight when he gets his tea, but pokes out a great deal when in close-up starts admitting his own guilt. (01:01:35)
Continuity mistake: Lombard trips going up the stairs in the dark; he falls on his right side, but he waves the others to go up lying on the opposite side, facing the opposite way. (01:04:30)
Revealing mistake: The suit of armor is knocked down by a hand, but when we see it fall there's a string pulling it for a more spectacular fall. (01:04:35)
Continuity mistake: And then there were four. They all are in the same room and Dr. Armstrong asks Ann Clyde what was she doing at the opposite end of the corridor. During the exchange, Shirley Eaton's hair is in front of her left shoulder but is or isn't in front of her right shoulder. (01:08:40)
Other mistake: Lombard supposedly just pretended to drop the key inside the chandelier while he palmed it instead, but A) you can see the shadow of the key in the glass bowl and B) the noise comes with a timing and pitch that could be explained only by a key dropped, not banged against the rim. (01:11:05)
Continuity mistake: Ann is in bed with Lombard and after his reveal she asks him the name. Her hair was in front of her shoulder when she turned, and it's back behind it at the cut, and in front again at the next cut. (01:16:00)
Plot hole: Lombard is able to deduce that the doctor died hours before because there are no footprints around him, canceled by the snow that fell through the night. If that's so, then the doctor himself should have a considerable quantity of snow on his back and hair, and instead he has none. (01:22:40)
Continuity mistake: Spoiler; During the confrontation between the two last Indians, there is a clear position switch; her hair is in front or behind her shoulder when she says "This is how it hands." (01:23:05)
Continuity mistake: Mr. Owen is playing billiards on his own when the last survivor joins them; at the very end, it turns out that the tray with the Indian figurines is on the pool table too too, but it was not there and nobody could have added it. (01:24:50 - 01:29:10)
Other mistake: There are heavy winds and persistent snow in an alpine resort, snowing every night, but throughout the whole movie even when Lombard goes to check the open door at night there's no hint of breath cloud on anybody.
