Sam Raimi's Army of Darkness (1992) pays homage to this film. When Ash has swallowed one of his little dopplegangers, he grows an eye on his right shoulder, which results in him splitting into two beings; Good Ash and Evil Ash. In this film, the reporter is injected with a serum and later develops an eye, which grows into a head, resulting in him splitting into a good being and an evil one.
This was an American production filmed in Japan using a mostly Japanese crew and a number of Japanese actors. It was shot in English. The film had various working titles, including "Nightmare" and "The Two-Headed Monster."
Sources state different release dates. The American Film Institute suggests it premiered in the YA in San Francisco on 3/28/62, at a run time of 72 minutes. Stuart Galbraith IV wrote in his book "The Japanese Filmography" that it was released in Japan in 1961 with an American premiere on 3/28/62, but AllMovie states it was released in the US on 7/1/59. Lopert Pictures released it in the US on a double feature with Eyes Without a Face (1960). In the UK it was released as "The Split". It was shown on "Elvira's Movie Macabre" and later released on DVD.
Originally released (as "The Split") as the second half of a double feature. The first film was a dubbed version of Georges Franju's Eyes Without a Face (1960) (aka "The Horror Chamber of Dr. Faustus").
For this English-language production, the producers needed two Japanese actors who were proficient in English. They cast Tetsu Nakamura (as Satoshi Nakamura), an actor who was born in Canada and went to school there, but moved to Japan in 1940. They also cast Jerry Itô, who was born in New York, so English was his native language.