"El Brujero" — The series's nickname among Hispanic fans, after the Netflix live action series was announced to have a Spaniard dub, in reference to the Blind Idiot Translations that European Spanish dubs are infamous for. Also "El Magias" (The magical one), "El brujerias" (The witchcrafter) and "Geraldo Revilla y su caballo maravilla" (Geraldo Revilla and his wonder horse). All usually pronounced with a THICK Spaniard accent.
Mythology Gag: One that's easy to miss is in the cutscene after you defeat Eredin. The move Geralt uses in that cutscene - taking the momentum from Eredin's parry and turning it into an attack of his own popped up way back in Blood of Elves in an early scene of Geralt training Ciri on the pendulums; specifically how to use that very move to successfully complete the exercise.
Name's the Same: Almost. Master Mirror's name is nearly identical to one of The Flash supervillains, Mirror Master. Strangely, they also share a colour-scheme (orange and green).
Flash, a prominent modder for The Witcher 2, was brought on as a gameplay designer for The Witcher 3
Stunt Casting: Polish dubbing for Blood and Wine involves two cases easily overshadowing Charles Dance in English dubbing, considering it's just an expansion pack and the roles are very minor:
Roach is voiced by Wojciech Mann, a famous radio speaker with a very characteristic voice. Just check yourself.
In the conclusion of Big Game Hunter quest, Geralt can visit the painting presentation. The woman making a lecture about monsters (virtually a nameless extra) is voiced by Krystyna Czubówna, a voice every single Pole knows due to her extensive work as a lector in documentary films about wildlife. It borders on Casting Gag, since she's yet again providing a lecture in style of documentary film, in completely serious tone, about fictional monsters.
Troubled Production: A mild example. If CD Projekt Red's Glassdoor page is any indication, development of the game happened at a breakneck pace that took a toll on employees, resulting in a staggering turnover rate.
Apparently, the game was originally scheduled to include a section where Geralt fights while ice-skating. The below article reveals that this section would've involved Ciri ice-skating in a boss fight against Caranthir, a Mythology Gag from the books.
Another article reveals a wide array of people, places, monsters and mechanics which didn't make it into the final product. One of the most notable alterations detailed is that Iorveth, one of the most prominent characters from The Witcher 2 and one of the most conspicuously missing individuals in the game, originally had a large role planned in the game along with the Scoia'tael. Unfortunately, for unexplained reasons, the story had to be cut in development and the writers decided to leave him out of the game entirely instead of just shoehorn him in somewhere else.
The game has won 250 Game of the Year Awards, along with 650 other awards. Combined, the game has over 800 awards.
The Taxman Cometh quest, the monster Chort of White Orchard, and the related cards in Gwent (the Chort and "Cow"), are in-game additions that reference player exploits that used to result in a lot of crowns very, very fast. Without clicking the wiki links and spoiling the fun, let's just say that killing six cows in White Orchard results in the Bovine Defense Force Initiative getting deployed.