In “First Blood,” Sam and Dean have been taken by the Secret Service for trying to assassinate the president. Castiel and Mary have no idea how to find them. The black ops imprisonment doesn’t feel like Supernatural, but perhaps that’s the point. Still, we’ll take monster hunts over secret American military installations any day of the week. Despite the incongruence, “First Blood” manages to include a few lines destined to become Supernatural classics, as well as emotional Winchester family moments. “