Continuity mistake: Near the end of the movie, just before the final battle scene, Leonidas drops his weapons and shield to the ground. He was holding the shield in the usual manner, and pushes it away to his left. When it hits the ground however, it is suddenly reversed and falls nearby with the front of the shield upward.
Continuity mistake: When the adolescent boy is facing off with the wolf, he is holding stick. At first, his left hand is about a foot from the left end of the stick. Cut to the immediate next shot, it is now holding the very end. (00:04:00)
Continuity mistake: When the old man is inspecting the baby at the very beginning of the movie, in close-up shots, his left hand is cradling the baby's head. In other shots, the hand is now under the shoulder. (00:01:15)
Answer: The scene is meant to show that Xerxes has exotic creatures/slaves from every corner of the world. In the reality of the film, a goat-headed musician would certainly qualify.