Continuity mistake: While Jaime and the High Sparrow are standing beside Myrcella's body in the Sept, in the overhead shot of Myrcella her right hand is placed over her left hand, but in other shots it's the opposite way. (00:18:30)
Continuity mistake: In one shot Sansa is writing a letter to Petyr Baelish, and is pressing a seal onto hot wax on the lower right corner. The next shot Sansa raises the letter, and the wax is gone. (00:39:45)
Continuity mistake: When Sam hands the bureaucrat the letter from Jon Snow, in the shots facing the bureaucrat, the wax seal is on the left side of the envelope (when seen from Sam's perspective). In the shots facing Sam, the seal is on the right side of the envelope.
Battle of the Bastards - S6-E9
Continuity mistake: When Jon Snow is all alone in the field drawing his sword to fight the incoming enemy cavalry, behind him we see an empty field. but seconds later as the enemy cavalry is near him they are met by Jon's own cavalry from behind. (00:37:30 - 00:38:20)
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