Continuity mistake: The first time the castaways meet Nemo, he is leaning on a spear with both hands wrapped around the shaft of the spear. At one point he puts his right hand down by his side. The shot changes and both his hands are instantly back on the spear.
Continuity mistake: When Herbert and Elena are being walled up in the honeycomb, the shots showing both people and the entrance show them leaning against the side wall. The shots showing them from the front show them leaning against the back wall. This is repeated every time the shot switches back and forth.
