The opening quote; "The blood-dimmed tide is loosed, and everywhere the ceremony of innocence is drowned..."; is from Yeats' poem "The Second Coming".
The name of the security guard in the first scene is Yeats - a nod to the poet whose poem provided the opening quote of the episode
First episode in the series with an introduction.
"Rotznasig carcaju," mentioned by Kelly in the trailer, comes from "rotz," meaning "snot" (as a noun or verb) or "glanders," and "nasig," meaning "-nosed," and "carcaju" which is the Spanish spelling of the word for wolverine adopted into English from French-Canadian (carcajou), making it a "snot-nosed wolverine" wesen.
Events at the beginning of this episode briefly overlap the events at the end of "Woman in Black".