Much of the film recounts actual historical events, including Shingen's death and the two-year secret, and the climactic Battle of Nagashino in 1575. Those scenes are also modeled closely on detailed accounts of the battle.
To secure part of the funding required to make the film, Akira Kurosawa teamed up with the Suntory Whiskey company to create advertisements for the drink on the set of "Kagemusha". These advertisements are included as extras on the Criterion edition DVD.
When Toho Studios couldn't fulfill the budget demands of the film, American film directors George Lucas and Francis Ford Coppola helped Akira Kurosawa by convincing 20th Century-Fox (still riding high after the success of Lucas' Star Wars (1977)) to fund the remaining portion of the budget in exchange for "Kagemusha"'s international distribution rights.