In the scene in which Harry is running to McGonagall asking permission to go to Hogsmeade, Hermione is seen wearing a green sort of sweater.

In the next scene, the one where Ron and Hermione are describing Hogsmeade to Harry and where the Fat Lady's portrait is discovered slashed, she is no longer wearing the green sweater, but the pink one which she wears in the later scenes. (Punching Malfoy, the Shrieking Shack, going back in time, all the end scenes)