Writer Tim Minear says on the DVD Commentary that he was working on his share of the script when a friend called him to tell him about the attacks on the World Trade Center buildings on September 11, 2001. Minear was horrified. Then he had to return to writing "Billy," because he was under deadline.
According to writers Tim Minear and Jeffrey Bell, the early fight scene between Lilah and Gavin was written to be much more vicious, with lots of punching and blood. The scene was revised to show Gavin throwing her against a shelf and attempting to strangle her, though in a later scene, it is clear that Lilah took some heavy blows to the face.
Angel is seen doing three things which are in his physical repertoire but which are rarely seen: (1) He leaps straight up over a high gate, without climbing it; (2) He smells a bloody hand-print low on a wall at a distance from a crime scene; and (3) a moment after speaking with Wesley, he runs super-fast.
Joss Whedon wrote the two conversations in Lilah's apartment (first with Angel and then with Cordelia).
Stephanie Romanov says the ending to this episode was one of her "favorite Lilah moments. It was the only time Lilah was a hero."