Closeups of Ronnie's hands as she plays the piano for the first time clearly show a large wart or mole on the back of her right hand. But you can see that Miley Cyrus has no such blemish on her right hand.
When Will and Ronnie are arguing on the beach about her not wanting to be another in his long line of girls she is wearing a necklace. At one point she turns to leave and when she turns back around the necklace is tucked into the neckline of her shirt. Once again she turns to leave and when she turns back the necklace is back on the outside of her shirt.