Shout-Outs in The Big Bang Theory.
- Bottle city of Kandor, is mentioned in one episode.
- A more subtle example: Leonard, Sheldon and Penny watch an anime called "Oshikuro the Demon Samurai". That was an allusion to an episode of Two and a Half Men, in which the animated adaptation of "Oshikuro" (which was a comic book then) was being made, and Charlie had to compose the opening song.
- When Sheldon won a prestigious award and was nervous about giving an acceptance speech. He took a few drinks to calm his nerves, overshot the mark, and one of his hijinx was singing the periodic table of elements to much the same tune as Tom Lehrer. Actually it's a shout out to Gilbert and Sullivan as the tune he was singing to was "A Very Model of a Modern Major-General." Which is the same tune.
- Mega nerd Wil Wheaton wore a Fruit Fucker T-shirt in one of his appearances on the show.
- When the four come back from their Arctic expedition, Leonard, Howard, and Raj all have grown caveman-like hair and beards, while Sheldon has a perfectly-groomed goatee... just like the one alternate-universe Spock had.
- Sheldon's various superhero T-shirts. Most frequently seen is his Green Lantern t-shirt.
- In the episode guest starring Stan Lee, the judge who throws Sheldon in jail is named "J. Kirby".
- In the fourth season New Year's episode, the gang (plus Penny's current boyfriend, Zack) dressed up as members of the Justice League of America for a party at the comic book store. Others were dressed as the Fourth Doctor, a Hogwarts student, and The Joker, among others.
- This troper doesn't understand how Joker relates to the other 3.
- One more subtle: "The Apology Insufficiency" featured guest star Eliza Dushku. Towards the end of the episodes Sheldon tries to get Howard to forgive him for a mistake by "reprogramming" him.
- Sheldon's line "Of all the overrated physicists in all the labs in all the world, why does it have to be Leslie Winkle?"
- There are several shout outs to Battlestar Galactica. They range from the characters talking about watching the show to Leonard, as Howard puts it, "taking out his aggressions on innocent Cylons" (i.e. he destroys a Cylon action figure with a laser). Don't forget the Cylon Toast! Everyone loves Cylon Toast.
- Many shout outs to Star Trek both old and new. Penny gives Star Trek figurines to the guys, Sheldon is at first upset that he missed the Star Trek reboot then upset that he didn't get a Leonard Nimoy Spock standee, a quick Lt M'ress mention, Sheldon's feud with Wil Weaton, Sheldon compares their friends to a landing party ("Now we have a Dr. McCoy!"), and of course...."Do you know what this means?! I possess the DNA of Leonard Nimoy!!!"
- There was an ironic shout-out to Firefly in "The Staircase Implementation":Sheldon: "Roommates agree that Friday nights shall be reserved for watching Joss Whedon's brilliant new series, Firefly."Leonard: "Does that really need to be in the agreement?"Sheldon: "Well we might as well settle it now, it's gonna be on for years."
- Sheldon's journal in "The Bozeman Reaction" is a shout-out to Rorschach's Journal in Watchmen.Sheldon: Sheldon’s journal. Security system in place. However, sleep continues to elude me. I’ve seen the underbelly of Pasadena, this so-called City of Roses, and it haunts me. Ah, the injustice, I lie here awake, tormented, while out there evil lurks, probably playing ''Donkey Kong'' on my classic Nintendo.
- Strangely enough, there is no mention in that episode that Bozeman, Montana where Sheldon decides to move to was also the location in Star Trek: First Contact where humanity made first contact with the Vulcans. You'd think Sheldon of all people would have brought that up.
- Wil Wheaton's The Guild t-shirt when he appears on Sheldon Cooper's Fun With Flags
- Sheldon's frequent quoting from the extremely detailed Housemate Agreement, right down to paragraphs, sections and subsections, evokes Rimmer's obsession with the Space Corps Directives on Red Dwarf.
- In fact, Sheldon owns all sixty-one released episodes of the BBC series "Red Dwarf", as revealed in "the Friendship Contraction".
- And... the whole idea of Howard going up into space as the world's least likely and most temperamentally unsuited astronaut. Everybody, including university benefactor Mrs Latham, makes dismissive remarks about his being a "space plumber". Howard soon finds out he's only there to do the equivalent of servicing the chicken-soup dispensers. His quirks make him the butt of the joke from more macho astronauts. While entranced with the view at first, he soon comes to regard it as excruciatingly dull. DoesThisRemindYouOfAnything?
- And in the one where Howard gets into an embarrassing situation with a robot arm, he programs the arm to respond to a snarky Sheldon comment, by having it turn to him and jerkily, but very obviously, making a finger-gesture. This is not the American middle finger, but the British V-Sign with two fingers. Compare the skutter (maintenance robot) in Red Dwarf who makes a similar derisive gesture to Arnold Rimmer after being provoked by a similar superior sneer.
- Bernadette proving to Howard that she can fake realistic laughter at his jokes is a pretty clear reference to the fake orgasm scene in When Harry Met Sally....
- Stuart's comic shop not only features the usual geek properties, but also posters and swag from licenses not overly known in the non-geek mainstream like InuYasha and Mirror's Edge.
- In "The Cooper Extraction", several What If? scenarios are explored. Two of them contain shout outs to well known stories. Penny ends up with nice but dimwitted Zack Johnson. They live together in Penny's apartment. Zack is so naive that he spends their rent money to buy magic beans, in a Shout-Out to Jack and the Beanstalk. Howard never moves out of his mother's home. We hear Debbie Wolowitz shouting for food, claiming that she is starving. Howard brings her food. The face of Debbie is revealed to be that of a mummified corpse. We hear "Mother" say: "You’re a good boy, Howard, such a good boy." Howard has simply gone insane, treating his dead mother as still living, and having conversations with her. Howard, who narrates this scenario, leaves ambiguous if his mother died of natural causes, starved to death, or if he killed her. The entire scenario is a Shout-Out to Psycho.
- In "The Alien Parasite Hypothesis", Sheldon and Amy are performing a differential diagnosis to determine what had caused her reaction while she was out with Penny and Bernadette (she met Zack and got turned on). Aside from the fact that both of them are arguing what her problem could be, one will notice that they are using a whiteboard, and lupus is listed as one possible cause.
- In The Holographic Excitation, there is a blatant shout-out to Sir Terry Pratchett's Discworld books. Specifically, the The Science of Discworld series, co-authored with prominent British scientists, in which Pratchett's fantasy world is used to mirror and illustrate developing scientific thought. In the books, the wizards of Unseen University (among them a rather nerdy type with glasses who affects a big baggy parka) accidentally create a bizarre pocket universe centered on a spherical world which orbits its sun. Stuck for what to do with it, it ends up gathering dust inside a protective glass sphere on somebody's desk. Meanwhile a geeky glasses-wearing scientist in a parka fires up holograms of Earth, planets and solar system to please his girlfriend. Leonard speculates that everything might just be one giant information-gathering hologram, being read by intelligences an unguessable distance away... The creation of the pocket universe in the Discworld — including Planet Earth — was done with the specific intention of averting a seriously Big Bang (at least in their universe), by diverting a lot of dangerously destructive energy down a harmless path... the secret of the Big Bang is down to a bunch of semi-sane Wizards who are, within their own University, every bit as asocial and strange as those at Caltech.
- One of the authors of The Science of Discworld, Professor Jack Cohen, is well-known in US academic circles. In one of the books he explains the torrid time he had trying to convince a hostile audience of the truth of evolutionary theory. He was in East Texas at the time getting heckled by Creationists. The Science of Discworld books — especially the second — are peppered with "common ground" references to people, science, and events in science also covered in TBBT. These shared references occur beyond all reasonable expectation of coincidence.
- And after seven or eight seasons where Amy casually refers to all primate cousins of humanity as "oh, just monkeys", she suddenly ascends a level and ticks off Sheldon for terminological inactitude - when he refers to orang-utans as "monkeys", Amy emphatically corrects him and points out an orang-utan is an ape, Sheldon. She considers this point to be very important...
- The (broadcast in 2013) episode "The Raiders Minimization" partially revolves around Sheldon having Raiders of the Lost Ark ruined for him by Amy, who points out that Indiana Jones is basically a Pinball Protagonist who has no real effect on the plot of the film. At one point in the 2012 novel This Book Is Full of Spiders: Seriously, Dude, Don't Touch It, David Wong mentions his girlfriend Amy ruining Raiders of the Lost Ark for him by pointing out that Indiana Jones is basically a Pinball Protagonist who has no real effect on the plot of the film.
