i can´t speak for the movie, but the comic is hardly an attempt to recreate history; you just have to look at what way are each character drawn. Greeks, specially spartans, dress a loincloth, if at all. Their weapons and armor are very simple, without any decoration. The persians, on the other hand, wear extremiely elaborate clothes, a couple pounds of piercings, and the arrow tips are so elaborate that they can´t be functional at all. Ephialtes isn´t just deformed: he´s hideous, barely recognizable as human; the oracles that forbid Leonidas to fight are horrible too, skinny monsters covered in blisters. Miller didn´t care for historical accuracy: he wanted to set a brutal contrast between spartans and persians as living metaphors for freedom and opression.