There is a scene where Beckett is on the train and the cop who is after him describes the details of peeing/ pooping that happen as a result of being tased. Nobody physically soils themselves though.
Head smashed onto pavement in multiple scenes- blood comes out but the head(s) are not completely crushed/ squashed. First scene happens towards the beginning during the car crash. In the final 10 minutes two or three heads are smashed onto hard surfaces until unconscious.
Main character revisits the site of the car accident (after he gets out of the hospital, probably around 15-20 min mark) and empties a bottle of pills into his hand. Not sure if the pills are lethal but it's implied that he is contemplating taking the handful. Before he took them he was interrupted.
White people are trying to kill the one black character throughout the entire movie. I won't post spoilers, but if you're not comfortable with white on black violence this probably isn't the movie for you. With that said, the reason these people are after him is not race related.