The magnificent 3 (1980)

After getting into a brawl in a Discotech in Dominica, three strangers; a Japanese tourist (Yasuaki Kurata), a Chinese restaurant worker (Tony Poon) and an American (!) painter (Tadashi Yamashita) find themselves thrown in jail together and left to rot there. Just when things seem their grimmest, the three are released, their bonds posted by an ex Army General. His intention is to put their supreme fighting skills to use against his family's black sheep, a powerful mafioso who employs top fighters from all over the world as protection.