This was Takeshi Kitano's only American film he ever made. In an interview, Kitano said that he did not like the final result of Brother and that he regretted his "Hollywood adventure", which was supposed to bring him a wider audience. As a result, Kitano said that he had no intention of filming outside Japan again.
Takeshi Kitano reputedly had problems working with Masaya Katô. Kato had his own ideas, and Kitano would get so upset that he would yell at him. In the scene where Aniki tells Shirase to put out the cigars, it is really Kitano yelling at Kato.
The body count is 78.
The dead bodies found in the headquarters (toward the end of the film) are arranged in the Japanese symbol (kanji) for "death".