I was watching the movie with my friends and we all noticed this. When Tony, Virginia, and Wolf are in the sewer (or whatever that watery place was) trying to get in the castle, they would obviously come out soaked. That's what they look like during the frog scene, but when you see them again they are completely dry! There wasn't a very long period of time before you saw them again and i don't think a hairdryer would work in that place.