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.
The Great Dictator (1940)
1 revealing mistake
Directed by: Charles Chaplin
Starring: Charles Chaplin, Paulette Goddard, Henry Daniell, Jack Oakie, Reginald Gardiner
Continuity mistake: During the middle of the film, a butler comes in and out of the Dictator's office several times repeatedly. The door is open and shows the corridor outside the office, casting the shadow of a window off-screen. The shadow changes from small to big bewteen shots.
Schultz: You must speak.
A Jewish Barber: I can't.
Schultz: You must. It's our only hope.
A Jewish Barber: Hope.