The door security code used (75309) is the last 5 digits in the famous 80's song "867-5309/Jenny" performed by "Tommy Tutone"
When Tony says to Ziva that she "Kimbo Sliced" through the attacking guards, he was referring to a Miami streetfighter who became wildly popular on the internet; he turned pro (UFC, MMA) at age 34. He died of a heart attack at age 42.
At the beginning when the soldier asks Tony, "What's your clearance?" Tony replies, "About 6 foot one and a half." This is in fact the height of Michael Weatherly.
At the beginning of the episode, Ziva comments that Tony needs a "tension breaker." One of the most notable "tension breakers" was during the final exam in Summer School (1987), starring Mark Harmon
Ducky's line "I am not unfamiliar with the discourtesies of the spy game" could be taken as a nod to David McCallum's role as Illya Kuryakin in The Man from U.N.C.L.E. (1964).