When Zoe (Scottie Thompson) returns the hat, Reddington (James Spader) refers to himself as "Kenneth Rathers." In 1986, CBS news anchor Dan Rather said he was attacked by someone who repeatedly asked "Kenneth, what is the frequency?"
Phillis Somerville, who plays the mother of Carel Struyckens character, is 4 1/2 years older than him.
Keen's screen name "Elsa" is a nod to the lioness in "Born Free"