Raj is supposed to be unable to speak whenever a female is nearby, but he's shown responding to Leonard right before Penny, who's in the room, offers to be on his Halo team.
Sheldon criticizes Penny's decision to sleep with her head facing the door, however in "The Hamburger Postulate" he sleeps facing the same direction.
As of the first airing of this episode, BBC America did not show Doctor Who at 6:15 in the morning on Saturdays when Sheldon claims to watch the show.
When Penny stays over at Leonard and Sheldon's, when they wake up it's Saturday, meaning Halo night was Friday night, but later in the episode Sheldon alludes to Halo night being every Wednesday.
Penny: Can I hide out here for a while?
Leonard: Sure. What's going on?
Penny: Well, there's this girl I know from back in Nebraska, Christy. Anyway, she called me up, and she's like "Hey, how's California?" And I said "Awesome," 'cause, you know, it's not Nebraska. And the next thing I know, she's invited herself out here to stay with me.
Sheldon: (checking his watch) 8:08!
Leonard: (to Sheldon) Shh!
Penny: Anyway, she got here today, and she's just been in my apartment yakkety-yakking about every guy she's slept with in Omaha, which is basically every guy in Omaha, and washing the sluttiest collection of underwear you've ever seen in my bathroom sink.
Howard: (sexually aroused) Well, is she doing it one thong at a time or does she throw it all in? Like some sort of erotic bouillabaise?
Penny: (to Leonard) He really needs to dial it down.
(after long deliberation in the restaurant without result)
Koothrappali: Can we please make a decision? Not only there are children starving in India, there's an Indian starving right here!
Sheldon: I don't know how, but she is cheating! Nobody can be that attractive and this skilled at a videogame.
Leonard: You know, Penny, we make such a good team, maybe we could enter a couple of Halo tournaments sometime.
Penny: Or we could just have a life.
Penny: (barges into apartment) Hey, guys! My friends and I got tired of dancing so we came over to have sex with you.
(The guys continue playing Halo)
Penny: Told ya.
(Penny and her friends leave)
Sheldon: Why did you hit pause?
Leonard: I thought I heard something.
Leonard: No, never mind.
Sheldon: I'll watch the last 24 mintues of Doctor Who, although at this point it's more like Doctor Why Bother.
Leonard: If you don't like this Christy, why are you letting her stay?
Penny: Well, she was engaged to my cousin while she was sleeping with my brother, so she's kind of family.
Leonard: Sheldon, think this through, you're going to ask him to choose between sex and Halo.
Sheldon: No, I'm going to ask him to choose between sex and Halo 3. As far as I know, sex has not been upgraded to include high-def graphics and enhanced weapons systems.
Leonard: You're right. All sex has is nudity, orgasms, and human contact.
Sheldon: My point.
Leonard: What's wrong?
Penny: Well, Howard and Christy are kind of hooking up in my bedroom.
Leonard: Are you sure?
Penny: Look, I grew up on a farm. From what I heard, they're either having sex, or Howard's caught in a milking machine.
Howard: Oh, by the way, where did you get that loofah mitt? Yours reaches places that mine just won't?
Penny: You used my loofah?
Howard: More precisely, we used your loofah. I exfoliated her brains out!
Leonard: Can't you see that she's using you?
Howard: Who cares? Last night she pulled off her blouse, and I wept.
Penny: Look, Howard, I know her, okay. She'll sleep with anyone as long as they keep buying her things.
Christy: (finds Howard) There's my Little Engine that Could. (Howard and Christy make out)
Sheldon: Well, there's one beloved children's book I'll never read again.
Leonard: You have a TV in your room. Why don't you just have breakfast in bed?
Sheldon: Because I am neither an invalid nor a woman celebrating Mother's Day.
Penny: Wait, Sheldon come back. You forgot something.
Penny: This plasma grenade.
(Explosion sound on the tv)
Penny: Ha. Look it's raining you.
Sheldon: You laugh now, but wait till you need tech support.
Penny: Hey, if you guys need a fourth, I'll play.
Leonard: Great idea!
Sheldon: Uh, no. The wheel was a great idea. Relativity was a great idea. This is a notion, and a rather sucky one at that.
Sheldon: Why? Oho, Penny, Penny, Penny.
Penny: Oho, what, what, what?
Sheldon: (as Penny picks up the controller) This is a complex battle simulation with a steep learning curve. There are a myriad of weapons, vehicles, and strategies to master, and not to mention an extremely intricate back story.
Penny: (explosion from the TV) Oh, cool! Whose head did I just blow off?
This episode's end titles has Chuck Lorre's Vanity Card #193.
The German episode title is "Das Vorspeisen-Dilemma", meaning "The Appetizer Dilemma". The French title is "Le Paradoxe du ravioli chinois", the Italian title is "Il paradosso del raviolo a vapore", and the Spanish and Mexican title is "La paradoja del Wan-Tun", all exact translations.
International Airdates: Turkey: October 28, 2008 on CNBC-e;Czech Republic: May 19, 2009 on Prima COOL; Germany: August 22, 2009 on ProSieben; Slovakia: August 25, 2011 on Markiza
Christy refers to Howard as her "Little Engine That Could", playing off the title character from The Little Engine That Could.
Responding to a knock at the door, Sheldon queries, "Oh, what fresh hell is this?" a phrase author and poet Dorothy Parker would reportedly answer her phone with.