Continuity mistake: Just before Kong is gassed and captured, he picks up someone and bites his head. In a close up, he has them by the legs, then in the long shot he is biting their head. (01:22:00)
Continuity mistake: In the gala scene, Zeppo explains that Groucho is always on time and will arrive at exactly ten o'clock. Everyone starts singing the first big musical number, "When the Clock on the Wall Strikes Ten." There is even a shot of a clock set to ten. In the middle of the song, the clock strikes... six.
Continuity mistake: While Peggy's singing "42nd Street" for the show's premiere, she suddenly goes from tap-dancing on stage to being on top of a car's roof right in the middle of her performance. (01:24:01)
Continuity mistake: In this 1933 Mickey Mouse short, Mickey dreams he is in a mad doctor's castle. He opens an inner door and finds a second door behind it. He then finds a third, fourth and fifth door. When a sixth door swings open and he is able to enter the mad doctor's lair, the other five doors have vanished.
Continuity mistake: After Jack strangles the police officer there are 3 guys by the door - he knocks down one of the them but in the next shot there is just one man left.
Continuity mistake: The first time we see the fireman's wedding photo, she's on the left and he's on the right. The next time we see it, their positions are reversed. (00:12:05)
Continuity mistake: When Oliver's wife comes to see him in the dining room, you can see she is wearing frilly sleeves. But when she goes into the kitchen in the next shot, the sleeves have gone.
Continuity mistake: Igor's face is not disfigured on New Year's eve 1933, when he looks out at the crowd. The next scene in the morgue he is disfigured.
Continuity mistake: When both Stan and Oliver walk into a plank that's being carried, in the background there is a jumbled pile of timber. But in a close-up of Stan and Oliver sitting on the ground, it is now a tidy pile.