Game Of Thrones Season 6: 8 Things You Might've Missed In 'Oathbreaker'
4. Whent Missing
As the Tower of Joy scene is recalled in the books, there were three members of the Kingsguard present: Gerold Hightower, Arthur Dayne, and Oswell Whent. In the show's version of events, however, there are only two (and while Dayne is called by name, the other could've been either of them, but the actor's confirmed he is Gerold Hightower).
This might just be the show streamlining things a bit (Ned Stark's also down a man compared to the books), but it doesn't fit with the continuity of the show. When Joffrey is reading through the White Book, which tells of all the brothers of the Kingsguard, you can see Hightower's page next to Dayne's, and it details his death, reading:
"Died in the Red Mountains of Dorne alongside his sworn brothers Ser Arthur Dayne and Ser Oswell Whent after refusing to bend the knee to the new king Robert Baratheon. All were defeated by a small force led by Lord Eddard Stark of Winterfell."
So Oswell Whent was supposed to be there. An error, or is he inside the Tower?