Are you kidding me?!
What kind of rapist takes his time like that with a girl in a public underpass? He was coked out of his mind so he would've been more paranoid than that. Rape scene took too long to be believable. If he has her in his own private quarters that's one thing, but for it to go on that long in an alley? Not realistic.
Also, the line that got her down there in the first place is very silly. "Take the underpass, it's safer." The underpass is safer after dark than a taxi? Who would ever believe a nonsensical thing like that? Not even someone with Down Syndrome would believe that. The fact that she just went for it because a stranger said so is ridiculous.