Work hours for someone underage...?

-I you are under 18 the latest that you can work until midnight so if someone underage had to work until 2 am or so and got pulled over would they be in trouble for being out past curfew even with a clock out slip since they weren't even supposed to be working that late anyways? Because my boyfriend is 17 and works at mcdonalds and on the schedule he was supposed to work until 11 but he doesn't get off until 2 am can they do that? Or is it against the law?ye its fine