The original Engineer of the entire Black box system is played by the same actor who played the Computer savant Laslo in Real Genius. The character of Laslo went into seclusion after some tech he created was misappropriated by the Govt to create a weapon.
For others, he's more recognizable as Broots, another computer genius.
Isiah Mustafa is Cyrus, a rogue Division agent turned arms dealer.
Truth in Television: The episode where Division attempts to kill a Georgian prince has a background in reality. There really is a Monarchist tradition in Georgia (though it's been absent from power for 200 years), and there really was a dynastic squabble settled by the two lines marrying recently, in 2009. All the personal stuff was fake, though.
Also, Nikita picking at her food in the suburban mealtime in 1x20 because it was a pot roast. She apologises when the kid says she is "busted". This is an allusion to Nikita's actress Maggie Q's real life veganism and animal activism. She is also well-known for ensuring that she works in places that do not use fur, and has changed this when working on certain projects before.
Homage: The scene in episode 16 of season one, where Alex, in her drug-induced haze, "escapes" Division and uses a ceiling hatch to go aboveground only to find herself in Russia in the snow is eerily similar to a scene in the Dollhouse episode "The Attic".
Retroactive Recognition: In "Alexandra," that's Kenzi as Alex's friend from her sex slave days. And then Lauren as a terrorist four episodes later ("Girl's Best Friend").
Nikita's dead fiancee is named Daniel. There was also a Russian spy (with a daughter!) called Irina.
The final two minutes of 2.10 are immediately identifiable to Alias fans as either an homage or a blatant ripoff of the final two minutes of "Almost Thirty Years", right down to the Not Quite Dead mother of our heroine, and a shocked "MOM?!".
Birkhoff calls the black boxes Percy's Horcruxes in "Betrayals".
In a later episode, he refers to Ari as "Lord Voldemort".
In "Shadow Walker" Division sends three trucks to deliver some money. Alex suggests that they see which truck is riding lowest "Hey, I saw it in a movie once". Later, when Birkoff does just that, Micheal snarks "I guess Birkhoff saw the same movie".
"Crossbow" turns into a 42-minute Shout-Out to Star Wars. The old Star Wars missile-defense sytem is mentioned, Percy's Kill Sat (dubbed the Death Star by Micheal) is called Crossbow (Like Chewie's bowcaster), Birkoff tells Nikita "May the Force be with you". The final plan is a trench run to fire a torpedo down...sorry, have Nikita drop down the silo to blow the computer room. Star Wars seems to be a favorite .
Birkhoff does a Dalek impersonation while hijacking a sentry gun.
"I am Wade's servo gun. I now betray my overlord. Exterminate! EXTERMINATE!
"Intersection" sees the cast in full snark mode: "Who watches the Watchman?"