Writer David Benioff said in a BBC interview, "The first time I saw [Edward Norton] on set he pulled back his hair and showed me his widow's peak. In the book, Monty Brogan has a widow's peak, but I hadn't mentioned it in the script. But Edward so wanted to be in character that he wore a prosthetic widow's peak for the entire shoot."
Edward Norton's character mentions about wanting to be the "girl in 'X-Men', the one that can walk through walls". Co-stars Anna Paquin, Brian Cox, Aaron Stanford and Dania Ramirez have all starred in the X-Men movies, as Rogue, General Stryker, Pyro, and Callisto respectively. The girl who can walk through walls is called Shadowcat.
Spike Lee: [glide] In the scene right after Jacob leaves the bathroom, he is seen motionless with the the background slowly panning out. Spike Lee often places actors on dollies to achieve this effect.
Spike Lee: [basketball] Both Monty and Naturelle played high school basketball; another scene depicts a playground game. Also, Frank is reminded by his boss that they have courtside seats for an upcoming game.