Toshirô Mifune entertained the cast and crew throughout the entire production with his refined culinary skills, bringing over a supply of Japanese meats, watercress, seaweed, and other ingredients. He would also exchange recipes for French and Italian dishes, including spaghetti.
The Japanese ambassador was played by Tetsu Nakamura, a Japanese actor known for his excellent command of the English language. It is believed that he coached the non-English speaking Toshirô Mifune for the English dialog required.
This movie made Charles Bronson a huge star in Japan. Around this time Bronson also did an ad for a Japanese cologne, for which he earned $100,000 for just four days work.
Before handing off screenplay duties, Ted Richmond based the idea for the film on a story he heard from an authority on Eastern history about a Japanese representative dishonored during a trip through the American West. He prepared a 15-page outline and courted Toshirô Mifune for the role during a trip to Japan in 1966, getting the first commitment for the international cast.
This movie stars US-born Charles Bronson, Japanese actor Toshirô Mifune, French actor Alain Delon, and Swiss actress Ursula Andress. Also, it was filmed in Spain by a British director Terence Young.