Gibbs runs into Special Agent David Brant, who basically says he is retiring. He is played by former NCIS special agent David Brant, who also served as NCIS Director 1997-2005. He retired in December 2005, the month after this episode aired.
Michael Weatherly says in the commentary for this episode that a filling came out during filming when the impression of his teeth was taken out of his mouth.
When Gibbs and Ducky are talking in the autopsy room about the bite mark on the leg, they speak of Ted Bundy. Mark Harmon played Bundy in The Deliberate Stranger (1986).
Given Agent DiNozzo's affinity for movies, he was channeling a scene from The Lord of the Rings: The Fellowship of the Ring (2001) where Gollum talks to himself in the lake water as if there are two separate beings when Tony interviews himself in the jail cell with Agent Gibbs looking on.