When Sister Margaret is shouting at teenage 26 just prior to beating her, 26 has a strand of hair almost horizontal just above her eyebrows after her face is slapped by Sister Margaret. This strand of hair then disappears, reappears then disappears again in successive shots.
Then in the next scene after the adult Michelle's face is slapped she has a strand of hair from her left ear to left eye which then disappears, reappears then disappears again in successive shots.