 FACT: At the final battle Algren tells Katsomoto about the battle at  Thermopylae. He tells him that 300 brave Greeks held of an army of 1  million Persians. This is in fact wrong. There were 300 Spartans (It  is believed that they had allies). But the Persians invaders were  only close to 150 000 men. Of course, stories from ancient times  describe the brave Spartas as heroes who stood up against 1 million  Persians, and at the time of the movie it might still have been  thought so.