The title "Mibu gishi den" literally means "Story of the Righteous Samurai of Mibu," and alludes to the "Ako gishi," better known in the West as the 47 Ronin.
The character Yoshimura Kanichiro is from the north of Japan (around the present day Iwate prefecture). Thus he speaks with a strong accent.
The Shinsengumi were a group of swordsmen employed by the Tokugawa shogunate. The group was created during the crisis period of the late Edo period when some groups in Japan wanted to overthrow the shogunate and return the emperor to a more central position. The Shinsengumi's initial name was "Ronin of Mibu" from which the title of the film was derived. Mibu happens to be a town where the group was formed.
In the movie, the Ono family uses the modern "biohazard" symbol as their 'mon' (family symbol).
Koichi Sato as Serizawa Kamo, and Sakai Masato star as Yamanami Keisuke in a 2008 Taiga drama called Shinsengumi.