During the end of the movie, when Jamie Ashen and the detective find Mary Shaw's puppet collection in the glass cases, look closely and carefully and you will see "Jigsaw" the puppet from the "SAW" movie series, sitting in the shadows as the camera pans through the room.

He is toward the foreground, but you must have a good eye due to the fact it is sitting in the dark. I think he is placed near some sort of post or column. For those who don't know, the writers and creators of the SAW movies are also the creators of this movie... hence the clever easter egg. Hope you can find it, enjoy!