In spite of his youthful appearance and reckless behavior, the bard Dandelion is supposed to be in his late forties by the time of the game's events. This is actually true to the books, where, a few years before, Dijkstra told Dandelion: "I know you're almost forty, look almost thirty, think you're just over twenty and act as though you're barely ten."
Doug Cockle (who voices Geralt in the English version of the game) said in an interview that he had not played any Witcher game previously in the series, but says that he bought a console this time to finally play Witcher 3 when it releases.
The master blacksmith in the game is called Hattori. This is a reference to Hattori Hanzo, the legendary sword maker in Kill Bill. Also, when you first meet him, he has given up sword making to make dumplings.
If you fall off a cliff in the game, there's a very rare chance of hearing the Wilhelm Scream.
In the quest Where The Cat And Wolf Play, Geralt can find a letter about the fate of various members of the Cat School; the writer mentions he doesn't know whether a Witcher named Schrödinger is alive or dead. This is a nod to the "Schrödinger's cat" paradox of quantum mechanics.
In Gwent, an archer card is quoted saying, "I aim for the knee. Always." This references a popular meme from "The Elder Scrolls V: Skyrim.
During the quest "Empty Coup" you meet a group of kids, one of whom is named Pete. A little girl in the group will say, "Pete says we're going to live in the woods and wear animal skins and make a tent out of leaves and never grow up". This is a clear reference to Peter Pan.
Near Bennic, you can find the entrance to a cave surrounded by skulls, blood, dead bodies, and a rabbit. You can only kill the rabbit with bombs. This is a clear reference to "Monty Python and the Holy Grail."
Throughout the world, you'll sometimes hear peasants say, "War - it never changes." A reference to the famous line in the Fallout series.
When Geralt first visits the dungeon of the Bloody Baron's castle, two NPC guards can be heard talking about a gimp in a nod to the famous scene in Pulp Fiction.
In Velen, there will be a cemetery nearby with two statues of angels near the front door. When you walk through the front door and then come back out, the two statues have moved. Whenever you turn your back on the statues and then turn around again, they will be looking at you. This is a reference to the Weeping Angels from Doctor Who.
The Game of Thrones easter egg present in the game consists of the player encountering the dead body of Tyrion Lannister (Major character from the Show/Book).
Before fighting the champion of Novigrad during the "Fists of Fury: Novigrad" the champion states, "You have been weighed, you have been measured, you have been found scrawny. In what world could you possibly defeat me." This quote is the same from the villain from the movie "A Knight's Tale," Count Adhemar.
During the quest, "The Great Escape", you can find a corpse in a tomb which, when inspected, will have Geralt say, "Hehe. Tomb Raider. Seemed this one liked eleven stuff", referencing Tomb Raider.
If you visit one of the brothels in novigrad, one of the girls will say "this is a material world and I am a material girl". A reference to the popular Madonna song "material girl"
When Geralt in conversation makes the hand motions for the sign "Axii", he is actually spelling it using letters from American Sign Language.
Longclaw is a sword that can be found in the game. It references Jon Snow's sword from "Game of Thrones."
While Geralt is in Skellige, he can claim a bounty on the Grossbart Brothers with the help of a bounty hunter called Djenge Frett - an obvious homage to Star Wars' Jango Fett.
When fighting the fallen knights in the DLC storyline Hearts of Stone, they will say things like "Ohh, what a day. What a lovely day!" and "I live, I die, I live again". A clear reference to the 2015 movie Mad Max: Fury Road.
The game allows to import saves from The Witcher 2; in absence of that, previous choices can be recreated in a conversation in the royal palace during the prologue, a couple of hours into the game.
In one of the "Fists of Fury" quests where Geralt participates in bare-knuckle fights, you have to fight against a guy called Durden the Tailor. Clearly a nod to Tyler Durden, Brad Pitt's character in "Fight Club", who also participates in bare-knuckle fights.
In Blood and wine, you can often hear a young girl saying "my brother got me this sword. I shall call it needle", this is in reference to Arya's gift from Jon snow in Game of thrones
The Nilfgaardian language, and the Elder Tongue from which it derives, is based off the Welsh language and its derivatives. Its culture is based off of ancient Imperial Rome. And its colour scheme are based off of the Holy Roman Empire.
The game includes an achievement/trophy called 'Let's Cook'. A reference to Breaking Bad.
Priscilla is voiced in the English version by Emma Hiddleston, Tom Hiddleston' s sister.
When Geralt's fighting bandits, there's a chance one will yell out "Your mother was a hamster and your father smelt of elderberries!" a reference to the French Guard in the Holy Grail.
Homage to J.R.R. Tolkien: one of the Wild Hunt generals is named Caranthir, like one of the sons of Fëanor in The Silmarillion.
The character the Bloody Baron bears many resemblances to Robert Baratheon from George R R Martin's series A Song of Ice and Fire. They both are former warriors who fail miserably at being good leaders. They are raging alcoholics and tend toward physical violence and shouting. Furthermore they have alienated their wives and children due to their rampant behavior. And finally the Baron's keep is full of stag skulls and antlers, possibly a direct homage to the sigil of House Baratheon, namely a stag.
Redania, its flag, colour scheme and people are reminiscent of Poland and Polish history.
The ship captain who leads Geralt to Skellige is called Wolverstone. A homage to a character in "Captain Blood".
In the English version of the game, Emhyr Var Emreis is voiced by Charles Dance, who many will know played Tywin Lannister in Game of Thrones (2011). Both are very capable military leaders, and have a no-nonsense attitude toward warfare amd leadership.
In one mission there is a reference to fifty shades of grey. "She would call him Cristian, and got him to call her Anastasia"
The book "Travel Between Worlds" contains references to "The Wizard of Oz" and "Alice in Wonderland." The land of Oz is replaced with Zo in the book.
In the Fists Of Fury: Novigrad quest line a bookie by the name of Claytop asks you to take a fall for a greater award in a fight against Gorgeous George, all of which is a reference to the plot and characters of the movie Snatch.
In the "Blood and Wine" expansion you'll 'battle' with a guy named 'Mancomb Seepgood', referring to Guybrush Threpwood, from Monkey Island. In addition, you'll later learn that these pirates 'duel' by hurling insults at each other to win.
In Blood and Wine, you find a camp site with a panther and a dead body. The looted letter begins with "Calvin!" and an angry letter from a Father over his son's pet panther named Hobbes. A reference to the comic strip Calvin & Hobbes.