The destruction of the black community center by the police.
The destruction of the slum in the beginning. The scene showed many innocent black men, women, and children losing their homes to bulldozers. It even showed white policemen bringing their guard dogs into homes and terrifying babies and women.
Paranoia Fuel: The policemen of your town are corrupt and racist enough to actually sneak into community centers and destroy them. Attempting to call them out results in more policemen threatening you and the witnesses. If you oppose the system, you may be arrested, lethally beaten, and your death's actual cause covered up.
Some Anvils Need to Be Dropped: The film doesn't hold back at all in showing just how horrifyingly brutal and oppressive life under Apartheid is but, considering it was still active at the time of it's release and world leaders such as Ronald Reagan and Margaret Thatcher refused to condemn or act against it, it was a message that needed to be heard and still does today.
Values Resonance: Biko's early scenes with Woods' where he calls out his liberal opposition to Apartheid while still benefiting from it and illustrates to him the nature of poverty and racism where black children grow up knowing that, no matter their abilities or ambition, they will never get the same opportunities as white children is very much in line with the growing discourse about race relations in the United States and other countries in the 2010's.