In the scene where Stiles, Lydia and Parrish go to see Meredith at Eichen House, whilst Brunski is walking away after handing the keys to Stiles, you can see Lydia briefly raise her middle fingers towards Brunski.
Jeff Davis confirmed at a convention that the well Liam was thrown into is the exact same well used in the 2002 horror film 'The Ring', and that he bought it off Universal Studios to use for the show.