3 actors from Seven Samurai in this film
I hadn't watched this movie in ages, but it was on cable recently and I noticed something new. Besides Toshiro Mifune, there are two other notable actors in this movie that were main characters in Seven Samurai.
The guy that was Kyuzo in Seven Samurai and the guy that was Gorobei are both in this film.
You can imagine John Frankenheimer was hellbent on getting any actors from chambara films to star in his movie.