Watch Supernatural Back to the Future 2 Season 5 Episode 13 Stream Online. Its all says in the title of this new episode, time traveling just like the movie. The episode is the Supernatural Back to the Future 2. In this episode, The angels send Anna back in time to kill John and Mary Winchester before they can conceive Sam knowing that if Sam was never born then Lucifer won't be able to use him as his vessel. The Supernatural Back to the Future II S05E13 will be aired at exactly 9:00 PM-10:00 PM EST on The CW this Thursday 2-4-10. Watch Supernatural Back to the Future II Season 5 Episode 13 Stream Online.