Does anyone know what happened to the horn? Since if I remember correctly it was shown in the tv show, found by Sam and I think he took it with him when he left south, or Idk if it was just in the books that he took the horn south, especially since from my understanding it should have been important to the plot of the Long Night, and I thought it would reappear. Edit: A lot of people commented it did not appear in the tv show at all, I believed it was this one which made a lot of sense in my head.
The horn of winter has not been referenced in the show at all, my guess is that in the books it was planned to play a part in allowing the others across the wall possibly by collapsing part of it, however in the tv series the dead dragon filled that plot hole. Now it is possible George Martin always intended the horn of winter to be a dead end plot and the dragon was always the way the wall would be breached, or maybe he will change this whole part of the story in the books. Until the books are released we will never know and even then we won’t know how much of the future story was lifted from the tv show rather then the tv show taking the original plans of the books.