When Nick and Adalind discuss their birthdays, Nick knows that Adalind's birthday is April 14 and tells Adalind that his birthday is June 18. April 14 is actually actress Claire Coffee's birthday, and June 18 is really David Giuntoli's birthday.
Unlike the quotes that appear at the start of most episodes, the quote that opens this one, "History is the nightmare from which I am trying to awake," is not from a folk story or Grimm fairy tale. It's an only slightly altered version of one of the most famous quotations from James Joyce's _Ulysses_, episode two, which runs: "History, Stephen said, is a nightmare from which I am trying to awake." The speaker, Stephen Dedalus, is generally regarded as a stand-in for young Joyce, and is also the protagonist of his earlier novel, _A Portrait of the Artist as a Young Man_.
In the family tree, Nick is written down as born in 1982. David Guintoli was actually born in 1980.
This was the first episode written by Jim Kouf that he didn't co-write with David Greenwalt.
There was no "Previously on Grimm" introduction and a shortened introduction sequence to compensate for the inclusion of the episode's longer duration.