Common Sense Note
Parents need to know that the villain's nefarious activities include peddling heroin and turning drug-addicted women into international sex slaves. The girls are offered to the heroes, and there is brief female nudity in the bedroom, as well as imagery of a drugged-up, hippie-style party. Rampant martial-arts violence ranges from non-lethal bouts to kung-fu fatalities, with snapped necks, crushed bodies, and speared corpses. Watching it on a cropped, full-screen version loses the composition of the action setpieces; try to get a "letterboxed" edition instead.
Brief nudity -- bare breasts and backsides -- in a harem of girls supplied to martial-arts athletes like goodie bags (implicit in this scene is a stereotype about a black man's awesome sexual prowess; he selects several concubines, while a white hero settles for one).
Countless martial-arts poundings, many ending in death. Bloodshed as the villain utilizes a variety of slashing/edged weapons on his missing hand. A death via impaling. A female character, threatened with rape, kills herself with a jagged piece of glass (not shown explicitly).
Some racial stereotyping. Bruce Lee's character is stoic, upstanding, righteous -- but murderous in avenging his late sister. Producers thought U.S. audiences wouldn't accept an Asian lead alone. To appeal to the most racially diverse audience they back him up with two supporting good-guy fighters (said to be Vietnam War comrades), a white and a black American, who are a little more roguish (running from gambling debts, for example). Uniformed American police portrayed as racist thugs, the Asian villain as a white slaver (a movie stereotype going back to silent days).
Drugs / Tobacco /
The villain is a heroin dealer, and we see the results in both corpses with needle-marks in the arms of addicts and in a rather silly psychedelic drug-party full of face-painted girls.