When Ineni Hassan was holding a gun to Sydney's head while she was holding the ball of plutonium, he says in Arabic "nazzel ha shwaya shwaya", which means "put it down slowly." However since in Arabic language males and females are spoken to differently, he should've said "nazlee ha..." because "nazzel" is for males only.
Goof: When Sydney is chasing Anna through the basement after Anna stole the briefcase from the vault, Sydney removes her high heels on a stairway, to run faster. A couple of edits later, we see Sydney round a corner, briefly we can see her wearing RUNNING shoes...a moment later we see her barefoot again. And she is clearly barefoot again when she begins her little brawl with Anna!
Number 47: (hidden) When Sloane is talking about the device that Sydney stole in "Truth Be Told," there a serial number on screen: 6867-8795-245-487 8739.
Number 47: The model of the car is Quantum 6 27 -110.
The car which is unveiled in Madrid is a Vauxhall VX200 (Vauxhall are also know as Opel).
At the party Sydney attends, a butler at the door compliments her necklace, he says: "Que collar tan encantador", in English it means: "What a lovely necklace".
Goof: When Sydney is trapped outside the vault chasing Anna, during the lockdown, the vault's key pad reads "BLOQUEO ABAJO". This however doesn't mean lockdown in Spanish, at best it could mean, "blocked down below".
Goof: While Anna is escaping from the party she walks out the front door, and a guard asks her to show him her bag, the guard however didn't have a Spanish accent, it was more like an Argentinean one. Also the way he asks her to show it "Sra. Dejame chekar su bolsa", the line is full of verb inconsistencies and wrong words.
The corridor with the u-turn in the basement of the building where the party was at, where Sydney chases Anna, is the same one, where in Episode "Pandora" in Season 4, Vaughn to maintain a cover, shoots Dixon.
Two things about the ball of plutonium:
First, wouldn't the CIA be worried about Sydney's health if she is directly exposed to plutonium? Even if a couple of minutes can't do serious damage they should still be cautious.
Second, why is Sydney scared of dropping the plutonium? There's not going to be a nuclear explosion if it hits the floor.
Plutonium is very heavy. A ball that size should be a visible strain to hold up.
When Syd tracks down her Dad to talk to him, he gets out of his car without anything in his hands. He and Syd talk and he walks away from her with a briefcase in his left hand.
Sydney: Are you insane? Calling me in here for a social event? SD-6 has a division whose sole responsibility it is to track their agents and report back suspect activity. "Your girl" is risking her life, and you yours, every time we lay eyes on each other. So, do me a favor: don't be so friendly.
Lambert: I-I just love your spirit.
Sydney: That's heartening. Are we done here?
Sydney: See you when I get back.
Vaughn: No, actually, you won't. Uh, I'm being replaced by a senior officer. It seems I wasn't experienced enough to be your handler.
Sydney: I don't want it to be like that anymore, I'm just sick of it. I mean, I always had this feeling that maybe someday, I don't know, my dad and I would connect. That things could start to get better.
Francie: Well, you know my opinion of your dad.
Sydney: I know.
Francie: But listen. If you can find it in your heart to forgive him for being the kind of guy he's been all your life, which I would find impossible and could never do, then you should make a real effort.
Sydney: (reading one of Rambaldi's schematics) "Rudimentary Schematic for Transportable Vocal Communicator".
Sloane: The guy was drawing up plans for a cellphone around the time of the Ottoman Empire.
Dixon: Come on!
Sloane: Ridiculous, right? You know me, I'm not a new age kind of guy, I don't believe in the power of the pyramids, I'm not a big granola fan.
Vaughn: What can you tell me about this woman, Anna Espinosa?
Sydney: She was born in Cuba, raised in Russia. One of the last of the Cold War babies. Go-to Officer at K-Directorate for wet work and active measures. About a year ago, I had a meeting with an informant in Yugoslavia, low level, just a guy with intel who needed the money. Anna recorded the entire conversation with a parabolic mike from the building next door.
Vaughn: How do you know?
Sydney: Because as I was shaking his hand to leave, she blew out the back of his skull with a sniper rifle, even though she got what she came for. Her way of telling me I was way out of my league.
Sydney: Who am I talking to?
Vaughn: Your invisible friend.
Sydney: Good. Where are you?
Vaughn: Satellite relay station back in L.A., watching you from a two-hundred mile orbit.
Sydney: (looks up at the sky) My guardian angel.
Ana: I heard about your fiancé. Very sad. I thought perhaps it was a security execution sanctioned by your employer. Maybe you said something in your sleep you shouldn't have. But then why would you be here in service for the men that killed your true love?
Lambert: I hate to pull rank, but time is a factor here.
Sydney: Time is a factor here. You know how much time? Seven years. That's how long I worked for SD-6 before I found out who they really are. And now that I know, my days of blindly following orders are over.
Lambert: Who the hell do you think you're talking to?
Sydney: I know exactly who I'm talking to. Tell Devlin if Agent Vaughn isn't on the other end of this earpiece when I turn it on, the C.I.A. gets nothing.
Music from episode includes:
"The Beginner" by Miranda Lee Richards
"La Cienega Just Smiled" by Ryan Adams
"Rings A Bell" by Bill Bonk
"Go Get It" by Spookie Daly Pride
The episode's title, "Parity", is a computer reference. A parity bit is an bit at the end of a byte used for error detection. It's association to this episode seems to be the relationship between Sydney and Lambert, and his supervising of her progress.
Marshall: ... you'll probably want to dress nice, you know, dress to thrill.
A play on Dressed to Kill, the title of four movies, one of which is an adaptation of a Arthur Conan Doyle's story and the more recent one was directed by Brian De Palma in 1980.