Did you know that...
- Donald Bellisario (creator and executive producer) was in the U.S. Marine Corps as a Gunnery Sgt.
- Sean Murray (Timothy McGee) is Don Bellisario's step son, and Troian Bellisario (Sara McGee) is his daughter so they are actually related. Also Charles "Chip" Stirling is played by his son, Michael Bellisario.
- The names Leroy and Jethro are from Don Bellisario's father and grandfather.
- NCIS is set in Washington DC area but is really filmed in Santa Clarita, CA.
- Pauley Perrette (Abby Sciuto) appeared in CSI: Las Vegas, and Lauren Holly (Jenny Shepard) in CSI: Miami.
- Mark Harmon, Pauley Perrette, David McCallum, and Michael Weatherly all appeared as their NCIS characters in the final episodes of JAG to begin the show's spinoff to NCIS.
- The hand tools that Mark Harmon uses on the set of NCIS, are mostly his own.
- Sasha stopped acting on NCIS because she didn't realize the amount of physical work related with the show.
- Pauley Perrette was born in New Orleans and her character Abby is also born in New Orleans. And she has a Masters in criminology and sociology.
- Pauley's natural hair color is blonde and it's curly.
- Lauren Holly's favorite episode of NCIS so far is Season 4 episode "Brothers in Arms."
- Lauren was starring in "Chicago Hope" along with Mark Harmon.
- During training for his role as an NCIS special agent, Sean visited a federal law enforcement training center in Georgia, taking driving courses and practicing on the shooting range.
- DiNozzo's wealthy father cut him off from his inheritance when he was 12 years old because he decided to pursue acting.
- Weatherly's family made their money from importing Swiss Army knives. So Bellisario used that as the reason for DiNozzo's family fortune.
- The title of McGee's novel "Deep Six" is the name of an actual novel written by Clive Cussler. Deep Six refers to six fathoms deep. Being "deep sixed" is being dumped in the sea.
- The sound heard at the beginning
and end of each act, when the scene goes to black and white is Donald P. Bellisario making that noise into a microphone.
- In the opening credits, the aircraft carrier going under the bridge is a clip from the opening credits of The Presidio (1988), starring Mark Harmon as a San Francisco police inspector investigating a murder on the Presidio army base in San Francisco.
- When asked which other character they would like to play, only Harmon and Weatherly said they would not play any other character than the one they already play.
- When asked to recount their first paid acting job, Harmon declared that his was to be in a gorilla suit making gorilla sounds. McCallum got all nostalgic and remembered his father taking him from Scotland to London in 1948 or so, when he was only 12, to play one of the Princes in the Tower on a BBC radio play.
- Pauley Perrette was in a band called Lo-ball: a song from her album features on Legally Blonde.
- Cote de Pablo has a special coach to help her with all the languages she has to speak.
- DiNozzo is a fan of the shows "Airwolf" (1984) and "Magnum, P.I." (1980), both also created by Donald P. Bellisario.
- There is a picture of Donald P. Bellisario hanging on the "NCIS Most Wanted Wall" as a criminal and also in McGee's publisher's office as a successful author.
- Harmon is very unlike Gibbs in his attitude to people. He organises charity events to aid disabled kids.
- In Season 2’s “Hearts Break”, when Kate's phone rings, it's a polyphonic version of the NCIS Theme song.
- In “Twilight”, the snake is wrapped around a stand-in's legs, not Sasha Alexander's, but Michael Weatherly really did grab the snake.