At the slam dunk contest, after O completes his dunk, there is glass all over the court. When the kid comes to get the ball, you can see that all the glass is cleaned up and there again right before O throws the ball.
During the last basketball game of the movie, there is a shot of the coach, and you see some of the other team's boys warming up. Their school is on the front of their shirts. The school is Stratford, which being an Othello remake is a direct reference to William Shakespeare and his birthplace Stratford-on-Avon.