Continuity mistake: Although Clara kicks her shoe at the Mouse King's head, when she gets down from the mantelpiece, it is back on her foot with no sign of her having retrieved it.
Continuity mistake: When Clara and Nutcracker meet the two little children in the Gingerbread Village, Clara gives the little girl her doll back but not only does it disappear from the girl's hands, but it's still missing later on when they meet Captain Candy and Major Mint, and the doll remains missing for the rest of the movie, and she didn't have it when they left.