When Penny's friend Christy from Nebraska and Howard are in Penny's apartment and the guys need a 4th for Halo 3, Leonard suggests they play one on one and Sheldon has an issue with it. Leonard states the only way it's possible to play teams is to cut Raj in half. Raj responds with "oh sure cut the foreigner in half" when Penny is present in the room. Raj can not talk to women or while they are around him, but he did in this instance. However, Raj did not realize Penny was in the room, so his anxiety issue would not have prevented him from talking.
It's not until the next episode season 1 episode 8 where Raj realizes he can talk to penny while drinking.
The morning after the original Halo Night, Sheldon says he is following the routine he has followed every Saturday morning since he and Leonard moved into the flat. Hence suggesting that Halo Night is on a Friday. However, later in the episode, when they ask Penny to take part in Halo Night and she says for her it's dancing night, he asks her if she dances every Wednesday night. Yet the suggestion is that Halo Night is a fixed night of the week.
In this episode, Sheldon says to Leonard "If I could afford it, I would kick you out." In a later episode, he loans Penny $1,400 and says he has lots more if she needs it. Including some money in a super hero's butt.
In The Hamburger Postulate (2007), which aired two weeks prior to this episode, while Leonard and Leslie Winkle are in Leonard's bedroom, Sheldon sleeps on the sofa with his head facing the door. In this episode, he chides Penny for wishing to sleep with her head facing the door.
While making up the couch, and arguing with Sheldon about it, the string on Penny's sweater changes position. She hits it with her hand accidentally resulting in it ending up in her cleavage, it is still there when she turns around. The camera switches to a wide view and you can see that she doesn't move her arms anywhere near it but in the next close up shot it is hanging down again.
Leonard and Sheldon's Xbox 360 is hooked up to their HDTV incorrectly. The component and composite connections are on separate inputs on opposite sides of the TV. In that state, the players would have no audio on the HD input and be forced to play in standard definition. It is highly unlikely gamers as knowledgeable as them would make this mistake.
The sounds heard and actions described by Penny ("I just blew off your head!") do not match Halo's game play.
Sheldon says that reductio ad absurdum is a logical fallacy, when in fact it is both a logically valid argument form (sometimes called indirect proof), and a general argumentative technique.
Howard's mother, during a screaming match with Penny's friend/Howard's love interest, refers to her as "The Whore of Babylon". "Babylon the Great" aka "The Whore of Babylon" is a Christian reference to an entity found in the Book of Revelations. It is unlikely that Howard's mother would make reference to a Christian prophecy.
Correction: Many phrases from the New Testament have made it into common parlance and could have been used by a Jewish woman. This isn't much different from the fact that many Jewish/Yiddish words have made it into the English language and common usage, even by non-Jews.
Correction: Many phrases from the New Testament have made it into common parlance and could have been used by a Jewish woman. This isn't much different from the fact that many Jewish/Yiddish words have made it into the English language and common usage, even by non-Jews.
When Howard is trying to call Leonard Hofstadter on his phone the automatic voice recognition tries to confirm the identity several times and gets it wrong each time. However, when Leonard tries to call a fictitious name using the same phone, it calls Raj automatically without confirmation.
Upon awakening at 6am, Penny slightly panics and thinks she slept the entire day. She says, "I slep all day?" With no T at the end of slept. As a just awaking person from the Midwest would say in their somewhat tired slurry dialect.
As of the first airing of this episode, BBC America did not show Doctor Who (2005) at 6:15 in the morning on Saturdays when Sheldon (Jim Parsons) claims to watch the show.
When Penny (Kaley Cuoco) stays over at Leonard (Johnny Galecki) and Sheldon (Jim Parsons)'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.
In the morning, following Penny's first night, you can see a box of Mini Bites cereal on top of the fridge. After Sheldon says his cereal has turned to mush, the box of cereal has been replaced with a different type.
When Penny invites Sheldon, Leonard, and Raj to go dancing with her and a friend, Sheldon says they can't dance. Yet in 421 Sheldon says he is a proficient dancer, as he took dance lessons against his will as a child.
Sheldon points out that he has sat on the same place on the sofa every Saturday morning without fail ever since he and Leonard have lived in the apartment together. However, when Leonard moved in, there were two chairs where the sofa now is. Leonard bought that sofa later on.
When Penny and her friends show up at Sheldon and Leonard's apartment at the end to tease the guys about having sex with them, Raj is standing and yelling at the game, even though Raj famously cannot speak to or around beautiful women.