Trivia: There are a lot of Greek references. Cerberus, Tartarus, a messengers boots (Hermes reference) and the princesses. Twilight is the Greek word for friend love, or Philia. Cadence is Eros, or romantic love. Celestia is Agape, the love God has for mankind. Well, Celestia is kind of a god. Luna is Storge, love of a mother and child. This works because she has helped Scootaloo and Sweetie Belle in a motherly way. She was a mentor to both of them.Lily Harrison
Trivia: Nergal is the villain introduced in this episode. "Nergal" originally was the name of the Babylonian God of Fire and Guardian of the Underworld. In the Bible, he is one of the demons allied with Satan himself. In the series Nergal is associated with the underworld and fire.
Trivia: Its teaser trailers are, for the most part, out-take footage that doesn't actually appear in the episodes. For example, in the scene in which ShadowMoon and Mr. Wednesday first meet aboard the airliner, the teaser trailer uses completely different camera shots and different performances from the actors. In the actual episode, the camera shots and performances for the same scene are noticeably different.Charles Austin Miller
Trivia: When Jeff Randall goes to the "Glasgow Tenement" (just after the opening title sequence) watch the graffiti on the walls behind him. One piece of graffiti shows the "stick man" logo from "The Saint", over which is is written the words "IS BENT". This was an in-joke by the crew of Randall & Hopkirk (Deceased) as, at the time (September 1968) they were filming back-to-back episodes of "Randall & Hopkirk" and Roger Moore in "The Saint" at Elstree Studios - even to the extent of using the same props and scenery.