According to Jermaine 'Huggy' Hopkins, Tupac Shakur often walked off the set during filming. As a prank, Hopkins told Shakur that he was being fired from the film. When Shakur found out that it was not true, he started a physical altercation with Hopkins.
The trivia items below may give away important plot points.
In the original ending, Bishop lets go of Q's hand, deciding that he would rather fall to his death than go to jail. This was supposed to be a reference to an earlier scene in which Bishop watches the ending of White Heat (1949) and declares that he wants to die in the same way. Test audiences did not like this ending, and Paramount executives demanded it to be changed.