(at around 1h 6 mins) When Peter is with Mystique, they zoom in on her face to show her yellow eyes. After Peter's second request, her eyes are blue again for the next two zooms. After they show Peter drooling, Mystique's eyes are yellow again.
(at around 19 mins) When Lucy went into the wardrobe, a large number of objects poured on top of her when she opened it. However, when Edward goes in (at around 28 mins), there is nothing in the room and the wardrobe is neat and closed again. This is probably deliberate.
(at around 1h 14 mins) When Lucy, Edward, Susan, and Peter face the White Bitch's frozen army, you can clearly see the soldiers breathing and blinking as the characters walk around them. In the far back, someone's arm moves.