Continuity mistake: When Ralph is running from the hunters at the end and he finds the pig's head on the stick, he stops with his arms spread out a bit. In the next shot, even though you only see his head and shoulders, you can tell that his arms are now straight at his sides.
Continuity mistake: After Jack places the pig's blood on Roger's cheek, he then places it on his own. Look at the amount of blood on Jack's index finger. It goes from a little to a lot.
Continuity mistake: After the rock hits Piggy on the head and he dies, from one angle his eyes are closed but from another angle they're open.
Continuity mistake: When Piggy is killed, in one shot there's only a bit of blood on his head, but in the very next shot it's all over his face.
