Tyrion Lannister: Speaking for the grotesques, I'd have to disagree. Death is so final, whereas life... Life is full of possibilities.
Eddard Stark: Winter is coming.
Tyrion Lannister: A Lannister always pays his debts.
Starring: Lena Headey, Peter Dinklage, Emilia Clarke, Maisie Williams, Michelle Fairley
Tyrion Lannister: Speaking for the grotesques, I'd have to disagree. Death is so final, whereas life... Life is full of possibilities.
Eddard Stark: Winter is coming.
Tyrion Lannister: A Lannister always pays his debts.

The Last Of The Starks - S8-E4
Other mistake: During the scene in the banquet hall, as Tormund says "most people get bloody murdered, they stay that way", look at Daenerys in the background - a disposable coffee cup is on the table in front of her. This brown cup with a white plastic lid is nothing remotely like the style of cups they're all drinking from in the scene. HBO acknowledged the slip up and digitally edited it out on streaming services, reruns and future DVD releases.
Trivia: The horse heart that Daenerys eats was actually made of gelatin, and genuinely tasted dreadful - her physical revulsion at eating it is real. It had dyed pasta to simulate veins, and was injected with fake sugary blood, which attracted flies. The blood was so sticky and ended up covering Emilia Clarke to such an extent that after filming it glued her to the toilet seat.
Question: Is there any place in the books, movies, or directly from George R.R. Martin to say why the Game of Thrones world has such unpredictable seasons? Magical, Scientific, Alchemical (ie in-between).
Chosen answer: Well Magic does come to mind. The White Walkers bring with them the winter. Because of this, the seasons are very unpredictable. "Winter Is Coming" refers to this.
lionhead