Other mistake: Brandon is wearing gloves but Phillip is not when they kill David. Afterwards, Brandon removes gloves from Phillip's hands.
Rope (1948)
1 other mistake
Directed by: Alfred Hitchcock
Starring: James Stewart, Farley Granger, John Dall, Dick Hogan, Edith Evanson
Continuity mistake: When Rupert gives ice cream to Brandon, they are besides a wall between the living room and the entrance of the house but the shot later, they are on the other side of it.
Brandon: The good Americans usually die young on the battlefield, don't they? Well, the Davids of this world merely occupy space, which is why he was the perfect victim for the perfect murder. Course he, uh, he was a Harvard undergraduate. That might make it justifiable homicide.
Trivia: At first, this film seems to have only one scene and two shots, one outside and another inside. Actually, it is divided in a series of 10 minute continuous shots, 10 minutes being the maximum duration of filming possible without reloading the camera. Every 10 minutes, the camera zooms on a dark object and then cuts.