i highly suggest renting the dvd even if you saw this film in the theater. theres a ton of bonus footage and behind the scenes type of stuff that is really interesting.
one special feature that i really like is the history channel min doc on the historical accuracy of the film. all of the events are based on truth but obviously the story is fictional. it gives a bit of history on samurai and how their role in society had all but disappeared with feudalism. pretty intersting stuff. also some awesome "shorts" on the costumes and weapons used in the film. for sure worth checking out if not owning