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)
Continuity mistake: Taran picks up the special sword in the dead king's tomb. In a fight with one of the Horned King's henchmen, he leaves the sword's holster in the castle, only to have it reappear in the scene where Taran cleans the sword.