Gibbs rule no. 8: Never take anything for granted.
Director Shepard, upon being told by Agent Gibbs he doesn't realize she was still here late, sarcastically tells Agent Gibbs that she is a doppelgänger. This is the second time Gibbs has been told that word, with the first time in Doppelgänger (2005). He remarks to Director Shepard he does not know what it means.
The name on the undercover Metro Officer's fake license is Andrew Aidan Ryan. Detective Andrew Ryan is an officer of the Sûreté du Québec who is the love interest in Kathy Reichs' Temperance Brennan (Bones (2005)) novels. As Ryan first appeared in the 1997 novel "Déjà Dead", this alias foreshadows the true occupation of the dead man in "Probie."
Michael Weatherly has worked with guest star William Gregory Lee before on the TV show Dark Angel (2000). William Gregory Lee guests starred and played one on Max's "siblings " Zack was also a killer. Michael Weatherly played Max's friend/love interest/hacker Logan Kale.