At one point in the game, Joel mentions that he wanted to become a singer. His actor, Troy Baker, was once the lead singer for an indie-rock band called Tripp Fontaine.
Nolan North also has a moment where his character (David) alludes to a line that he said in a previous work released a year before The Last Of Us. During his confrontation with Ellie (if you let him talk for long enough after stabbing him for the first time), he says "you brought this on yourself."
An inversion of sorts, while the original concepts for Joel and Ellie had their last names as "Miller" and "Williams", respectively (see What Could Have Been below), Naughty Dog eventually decided to scrap all last names from the game. This hasn't stopped somefans from running with the scrapped names, however.
Coupled with Throw It In: The decision to make Riley Ellie's love interest came when talking to the writer of the American Dreams prequel comics, they said that "Ellie was attracted to Riley." The writer stopped them and asked if they meant attracted as in a "digging her personality"-way, or in a "sexually attracted"-way. They then spent a couple of weeks looking back at Ellie from the game, realized that there were nothing about her that leaned one way or the other and, after a go-ahead from Ellie's actress, decided to go with it.
Deleted Scene: A recent 2014 "Live Performance" of The Last Of Us revealed a scene that was meant to have been The Stinger, but got cut out. The scene (acted by Troy and Ashley, not animated) features Joel and Ellie some few months after settling at Tommy's, where Joel visits Ellie in her room and talks a bit about a woman Tommy has been setting him up with. Ellie still acts a little down after the outcome of their journey and Joel's lie. Joel then presents a guitar and plays a song for her, with Ellie thanking him when he's done. He then gives her the guitar as a present, and she playes a few notes on it after he walks out.
Doing It for the Art: Naughty Dog had to stand its ground to have Ellie feature on the game's cover, since the popular idea among publishers is that games with a female on the cover might alienate wider audiences. More about it can be read here.
BioShock Infinite: Both are AAA games with a heavy focus on narrative featuring guitar playing, Unscrupulous Hero protagonists voiced by Troy Baker, who both lost their daughter 20 years ago and are now charged with escorting a MacGuffin Girl named Elizabeth or a derivative of such, teaching her the ways of the world, and eventually turning against a black woman leading a revolutionary force.
The Walking Dead: Man takes care of a young girl in the midst of a zombie apocalypse.
Metro2033/Last Light: Post-apocalyptic Survival Horror story set in the ruins of a former superpower nation 20 years After the End, heavy use of Improvised Weapons, hostile environs that require a gas mask and a rechargeable flashlight, ability to choose between stealthy or loud approaches to combat, and even more guitar playing.
Enforced Method Acting: For one take of the final cinematic (which was turned into an interactive scene in the final game), Merle Dandridge was told to deliver her lines in a certain way and Troy Baker was independently told to keep going no matter what (he had been fumbling the prop gun during most takes). You can see the result in this behind-the-scenes video.
When acting out the cutscene during Fall where Ellie confronts Joel about leaving her, Ashley pushed Troy while saying "...everyone - fucking except for you [have left her]." The push was unscripted, but Druckmann thought it fit well and let it stay.
Fan Nickname: The infected are often jokingly referred to as "the mushroom people".
Some people have taken to calling the time before the infection outbreak as...well, Before. With a capital B.
In thisLet's Play, Geop and Skippy Granola take to calling Joel "Solomon Grumpy."
I Knew It: There was a Running Gag on /v/ that Ellie was gay after the opening scene of the Left Behind DLC was shown in a preview, where we see Riley biting her neck to wake her up. This ended up being completely true.
Lying Creator: Enforced. Naughty Dog felt the need to insist that you only play as Joel and never as Ellie in interviews because they felt the twist was so crucial to the story.
Tess was originally conceived as a major antagonist, harboring a grudge against Joel for betraying her in the past. More about it can be read here.
An AMA on reddit.com with game director Bruce Straley and creative director Neil Druckman revealed some interesting things:
Early in development, Joel's last name was given as "Miller" and Ellie's as "Williams," but Neil Druckmannrevealed that the decision was made to cut all last names from the final product. These names are still listed in the Japanese manual, however.
Joel rescuing Ellie from the operating room was originally going to be a cutscene, which can be seen parodied here (spoilers, obviously) with Troy Baker and Merle Dandridge singing the dialogue in the ending.
“Now when I was writing it I was writing it with the idea that Ellie is gay, and when the actresses were working they were definitely working with the idea that they’re both attracted to each other. That was the subtext and intention that they were playing with from the opening cinematic when they’re holding each other’s hands for too long, or when Riley bites her on the neck; there’s that chemistry there from the get go that was important for us so that we earned that moment when they kissed each other. So that it wasn’t just out of the blue but also wasn’t so overt that you’re like “Oh of course. Just get on with it.”
Both Neil Druckmann and Troy Baker have shown interest in Josh Brolin to play Joel in the movie adaptation, while Ashley Johnson's own personal choice for Ellie is Game of Thrones actress Maisie Williams, to which said actress has stated that she "wouldn't say no" to playing her. Whether these are the actors that will actually end up in the roles however remains to be seen.
Hugh Jackman is rumored to be considered for the role of Joel as well.