In defense of 300... I don't think it was meant to portray accuracy at all... but to be a representation of the story brought back to encourage the Spartans to fight. More or less an embellished war story.
I have studied a little bit on the "real 300" and realize its significance at the time.. and how it's like day and night between the actual event and the movie.
"The weakest soul, knowing its own weakness, and believing this truth that strength can only be developed by effort and practice, will, thus believing, at once begin to exert itself, and, adding effort to effort, patience to patience, and strength to strength, will never cease to develop, and will at last grow divinely strong."
- James Allen