Revealing mistake: The first morning the new Mrs De Winter is at Manderley, she goes to have breakfast, but when she attempts to pour milk into her coffee, there's no milk in the jug; she's just pretending to pour it.
Revealing mistake: During Fritz's fight with the giant anaconda in the swamp, James MacArthur's stunt double becomes apparent by virtue of a bald spot showing on the back of his head. (01:10:30)
Revealing mistake: In the scene where Cary Grant punches Jimmy Stewart: Jimmy starts falling back (and you hear the sound effect of the punch) when Cary's fist is a good 1-2 feet from Jimmy's face.
Revealing mistake: Chapter 3: Walking Bombs and Chapter 4: The Destroying Ray. They accelerated the movie when you see the robots, or walking bombs, to give the illusion of mechanical movements. The only problem is that when you see people fighting with them, their movements are also accelerated.
Revealing mistake: When Pinocchio gets in bed with Gepetto and Figaro, Gepetto puts out the light of the candle. If you watch closely, the light goes out a split second early.
Revealing mistake: When the defective shell is about to fall, the ground has no sand mounts. Couple shots later, now on the floor, the shell turns around following Chaplin. Watch and you'll see that a sand mount has magically appeared close to the shell to hide the white mechanism that makes the bullet turn.