Gibbs (Mark Harmon) is working on a crossword puzzle and says, 'TV drama, 8 letters down.' Tony replies, 'Umm. St. Elsewhere (1982).' Gibbs chuckles at the answer. Mark Harmon played Bobby Caldwell on 'St Elsewhere' from 1983 to 1986.
After Ziva slaps Goliath, Tony says, "Be glad she didn't have her slingshot," referring to the weapon David use to kill Goliath in the Hebrew Bible (1 Samuel 17:49). Ziva's last name, of course, is David ("Dah-veed"), pronounced just like the Biblical character in Hebrew.
When Goliath mentions Ares, they mention their Zodiac signs. DiNozzo - Cancer, Gibbs - Virgo, and Ziva - Scorpio. These are are the actual Zodiac signs of the actors.
Gibbs uses the phrase "More careful than Gotti." when describing La Grenouille. Armand Assante who played La Grenouille played Gotti (1996) in the HBO movie of the same name back in 1996.
When Ducky prepares to drive into his undercover meeting as a English arms dealer, he bolsters himself with the phrase, "Tally ho!" David McCallum previously played a British character in The Great Escape (1963) who was encouraged mid-mission to keep up his cover when James Garner's character whispered "Tally ho!" to him.