The first episode to have the red slash through Osama bin Laden's picture on the "Most Wanted" wall. It was obviously added post production, as it was only two days earlier that the al Qaeda leader had been killed by a U. S. Navy Seal team.
In one of the flashbacks to his days as a Baltimore PD detective, DiNozzo says to his partner, "Who'd want to be a Navy cop. I'd rather have the plague." Not only is he now a Navy cop, the 'Very Special' NCIS Agent, Anthony DiNozzo; in the 2005 episode "SWAK" he was infected with pneumonic plague.
In a flashback, it is revealed that Tony received his Mighty Mouse stapler from his old boss, Frank Raimey, as a result of him winning the Baltimore Police Department Pool Championship for the second year in a row. Raimey admits that he got the stapler from a garage sale.
In Gibb's flashback Special Agent Pacci says "My ulcer's killing me again. I'm telling you, this stomach is going to be the death of me." Although not the actual cause of death, but in the episode "Dead Man Walking" in Season 1, his body is found mutilated in an elevator.
At one point Abby says to Gibbs "xiexie" or "syesye" (depending on the romanization system used), which are the correct syllables for the common expression in Mandarin Chinese for "thank you"; unfortunately, however, Abby does not use the correct falling tone (the fourth tone); instead she utters those syllables essentially tonelessly.
There is a file envelope attached to the bottom of one of Tony's right desk drawers. You briefly see it as he looks for his phone. In the previous episode "Defiant" we learn that the envelope has different crime scene stickers from different agencies.