Continuity mistake: A couple of minutes before the end, when Louise and Frank embrace, from behind him her head is on his left shoulder; when the shot is reversed, her head is on his right shoulder.
Revealing mistake: During the flashback sequence showing Rocky's past crimes, two explosive devices are thrown at a shop window. Both bounce harmlessly off and land on the sidewalk, but the shop obligingly explodes anyway.
Audio problem: Shirley Temple is singing a medley of songs when she hits a block of wood with a stick. The sound effects are obviously not synchronized with Shirley's motions. (00:55:55)
Continuity mistake: Near the beginning, Cratchit drops his hat while getting hit by snowballs. In the other angle, his hat is back on instantly.