Visible crew/equipment: At the Wildling camp, before Jon and Ygritte go into the cave, there is a modern building, and clutter visible in the distance.

Game of Thrones (2011)
1 visible crew/equipment mistake in The Climb - chronological order
Starring: Lena Headey, Peter Dinklage, Emilia Clarke, Maisie Williams, Michelle Fairley

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.
Cripples, Bastards, and Broken Things - S1-E4
Daenerys Targaryen: If you ever lay a hand on me again, it'll be the last time you have hands.
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