Well, just because the city itself extends its serving time till 3am doesn't necessarily mean that HHN will extend till 3am. Unfortunately, that's also exactly what could happen - HHN and alcohol are possibly the two greatest things on earth by themselves, and when combined, are a powerhouse in terms of money.
I only say "unfortunately" when referring to the time extension because, after working from 6pm-2am on some nights, you get super, super tired. You'd be lucky to feel your legs after a long night of scaring, and I personally found it rare that, when asked to extend for another 45 minutes after my clock-out time, I would want to stay.
Drunk HHN-ers would just end up pissing me off if I had to stay an extra hour to scare someone who's too drunk to appreciate the effort (no offense to those who drink there, I wish I could, but an extra hour seems too much).