Continuity mistake: When Taran, Princess Elonwy and Fflewddur try to escape from the Horned King's castle, Taran opened the gate by removing the chains. The next shot the gate is closed and chained, the last shot the gate is open again, and the boat is pushed trough by Taran. (01:06:33)
Other mistake: When Dagg hits the soldier on the left while the fembot is distracting them, he falls over and the one on the left turns to see what happened. It then cuts to a different view and suddenly the second soldier just falls over without even getting hit.