The Ghost of Harrenhal - S2-E5
Continuity mistake: Brienne and Lady Catelyn are with their horses by a stream talking. Brienne's white horse is walked into picture and is very dirty. The next shot the horse is clean. (00:38:40)

Starring: Lena Headey, Peter Dinklage, Emilia Clarke, Maisie Williams, Michelle Fairley
The Ghost of Harrenhal - S2-E5
Continuity mistake: Brienne and Lady Catelyn are with their horses by a stream talking. Brienne's white horse is walked into picture and is very dirty. The next shot the horse is clean. (00:38:40)

Other mistake: As the surviving characters discuss the fate of Westeros, 2 plastic water bottles can be seen tucked behind the chairs they're sitting on.
Tyrion Lannister: The Eyrie. They say it's impregnable.
Bronn: Give me 10 good men and some climbing spikes... I'll impregnate the bitch.
Trivia: Cersei remarks to Tyrion that she had heard his nose was cut off during the Battle of Blackwater Bay. This is a reference to the books, in which part of Tyrion's nose was indeed cut off.
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