John Hagen: I'm just saying, it's a hell of a lonely road he's walking.
Calleigh: Well, that's why I'm walking it with him.
About seven minutes into the episode, the Assistant State Attorney confronts Horatio outside of the lab. When he describes the case and its evidence, he means to say "His DNA under her fingernails," but he messes up his line and says "His DNA under his fingernails," which makes absolutely no sense in the context of the evidence. The actor clearly flubbed his line.
Calleigh: Be still my heart.
This line pays homage to the ancient Greek poet, Homer, who quotes, "Be still my heart; thou hast known worse than this."
Horatio: We've got mail.
This line pays homage to the film "You've Got Mail" (1998).