Amy Acker is one of four stars from the CBS drama Person of Interest to appear in Supernatural. She was proceeded by Sarah Shahi in "Pilot" (Seas. 1, Ep. 1), Sterling K. Brown (2006-07), and Leslie Odom, Jr. in "Season Seven, Time for a Wedding!" (Seas. 7, Ep. 8).
When the sheriff tells Sam and Dean that he will arrest them or they can leave town, Sam says, "Door number two sounds good." This is a reference to the TV game show "Let's Make a Deal" (1960's to present).