Audio problem: During the Tea Party scene, the Mad Hatter and March Hare ask Alice to tell her story. After the Mad Hatter says "And when you come to the end, stop!" audio follows of the voice director saying "great," leftover from the original recording. (00:45:40)
Revealing mistake: When the boat is supposedly surrounded by a swarm of flies, they're really just relatively few flies trapped between two panes of glass in front of the camera lens. Evidence: whenever the camera moves, the "swarm" moves with it against the background, and you can even see some of the insects walking on the surface of the glass.
Factual error: All of the Lydia's lieutenants are wearing epauletes on their left shoulders.only lieutenant commanders were permitted to wear one on the left shoulder, while the right shoulder was reserved for captains of less than 3 years' seniority.
Revealing mistake: When The Indians launch their final attack (towards the end of the film), on a old outpost held by a small group of soldiers, Ward Bond is hit by a arrow which enters the right side of his chest. In the next shot you see Gregory Peck removing the arrow from the left side of Ward Bond's chest.