Other mistake: As the Telmarines advance out of the woods, there is a shot in which the mounted troops ride through a gap in the foot soldiers, then turn to line up in front. It is clear that this is a second take because the grass where the horsemen are about to ride is already trampled.
Revealing mistake: When Susan is in the forest and shoots her bow and arrow to hit the guy off his horse, the camera pans to the guy falling off his horse and the arrow can be seen still on the bow.
Answer: The one who stabs Miraz with the arrow is one of the Lords that promises support when Miraz is ordained King. He dies on the bridge (that the Telmarines built) when Aslan causes the waters to 'come alive'. The Telmarine who walks through the 'doorway' (to the world of men) with Miraz's wife and their infant son is Miraz's General. Earlier in the film, Miraz ordered this General to kill three of his men (after the Narnians stole the weapons), and during Miraz and Peter's duel Miraz ordered him to kill Peter if the dueling was not going in Miraz's favor, but the General chose not to. On the field, during the last battle, the General had an opportunity to kill Caspian, and again he chose not to.
Super Grover ★