For the phone book scene, a prop phone book was made out of foam and rubber, so that Keanu Reeves could genuinely smack Grill, played by The Game, with it. Although The Game insisted on Keanu using a real phone book, after one take in which he was hit with it, they switched back to the foam and rubber prop, because the real one really hurt The Game.
The film was shot in a grueling 43 days with very long hours for the cast and crew, according to director David Ayer.
The chase sequence in South Central really took place in alleys and back of people's houses which took over two nights.
Detective Tom Ludlow (Keanu Reeves) wakes up at the beginning to the same alarm sound as in Matrix (1999), where he played Thomas Anderson a.k.a. Neo.