During the scene when all the girls are dancing on the bar and pouring pitchers of water on themselves and each other Violet (Jersey) goes from having dry hair, then wet, then dry, then wet.
I think that you might be confused. Sometimes your eyes can play tricks on you, and maybe the lighting threw you off guard a bit too. I'm sure that directors wouldn't let a mistake like this pass. Okay, so in nearly every movie there are a lot of silly mistakes, but this one would be a bit big to let go!