The creators of the show may have been heavily influenced by the cult horror classic Silent Night, Deadly Night (1984) for this episode. The movie also follows the story of a killer in a Santa suit set out for revenge against the head nun of an institution who abused him.
The tender on the train is supposed to read "Lionel Lines." They covered the Lionel portion.
Mary Eunice (Lily Rabe): Well, I say... "Bah humbug."
Referencing the famous line of Scrooge in Charles Dickens' 1843 novel, immortalized on stage and screen. It tells the tale of Ebenezer Scrooge, who learns the true meaning of Christmas after being visited by the Ghosts of Christmas Past, Present, and Yet to Come.