The Bone Collector (1999)

Continuity mistake: In the scene where Amelia is driving the truck full of policemen to the scene of the second (Mrs. Rubin) murder, the shot changes a couple of times before it settles looking through the front windscreen at Amelia. Through the rear windscreen of the truck, you can clearly see the highway and all the cars on it behind them. Amelia turns the steering wheel sharply to the left, and you hear the screeching rubber-tyres-on-tarmac noise as if she really had swerved left, but the scene of the highway behind them seen through the rear screen does not alter at all - as if she was just going in a straight line all the way.

Amelia: I can't do this.
Lincoln Rhyme: You can do it. Yes, you can. Yesterday you stopped a train. You can do anything you want when you put your mind to it.
Amelia: Don't work me, Rhyme... Just tell me what to do next.
Lincoln Rhyme: Very slowly... walk the grid... one foot in front of the other. I want you to look around you now. Remember... crime scenes are three-dimensional... floors, walls and ceilings.

Trivia: The movie makers really wanted the audience to believe that Michael Rooker was the killer, rather than Leland Orser. So much so that Rooker actually played the killer in almost all the scenes where the killer wears a mask. When you see the eyes of the killer through the mask the eyes are Rooker's.

Question: There is a LOT of changes if you compare the film to the book, and most of them I understand, since you always have to make some changes. But why did they change such things as characters names and genders?