Tim Connolly, who played the father of Leonidas, was also Gerard Butler's stunt double.
The monologue spoken by the narrator when the film shows Leonidas and his men dead is actually found on the tomb of the real King Leonidas.
Some weapons used in the movie were also used from other movies such as "Alexander" and "Troy".
The flowing effect of the Oracle dancing scene was accomplished by filming the actress under water.
Black20 made a fairly popular parody trailer out "300" which made it into a PG version of the movie.
Colt's quarterback Peyton Manning was featured in a "300" sketch on Saturday Night Live.
Michigan State University has adopted aspects of the film in their sporting events, due to their teams all being the Spartans. A quote from the film, "Spartans! What is your profession?" is commonly chanted at various sporting events.
From 2007 to 2009, the quote of "This is blasphemy! This is madness!" "Madness? No. This is Sparta!" became a popular Internet meme, often consisting of an image of Leonidas superimposed into various locations, with text on the side of the image says "This is (name of the location Leonidas has been put in)!" It was also parodied on Saturday Night Live.
In the comic on which the film is based, the Spartans fight naked. This is meant to set up that that the story is being told by an unreliable narrator - Greek heroes are depicted in art contemporaneous of the war with Persia in the nude.