Michelle Feynman, who played the irritated mother during the surveillance scene at the end, is the daughter of Richard Feynman, the mathematician on whom Charlie Eppes' character is loosely based.
This is the 100th episode (excluding episode 0, which was unaired), as referenced ("100 episodes") in the opening shot (the black screen with data) with. It has several references to the first episode.
Kim Rossmo is mentioned. This is a real person, whose research led to a new method of investigation called geographic profiling. Originally from Canada, Dr Rossmo has been at Texas State University since 2003.
While on stakeout, Colby and Liz discuss "Sea of Love", and Colby asks if Liz is a "big Pacino fan". She replies that instead she is a big Michael Rooker fan.
When Larry recommends to Charlie that his approach "needs to be less elegant, more complicated" and Charlie replies "Haven't we had this conversation before?" it references almost the same suggestion Larry made to Charlie in the show's pilot.