The actor for Mumon is Satoshi Ohno. He is a lead singer with a pop group called Arashi.
Iga is an area in the modern Mie prefecture of Japan.
The historical background for the movie is largely true. It is set during the warring states era (sengoku jidai) at around 1579 when Oda Nobukatsu invaded the area of Iga and failed. His father Oda Nobunaga re-invaded the area in 1582 and destroyed the independence of Iga.
Oda Nobukatsu was a real historical figure who lived from 1558 to 1630.