A Knight of the Seven Kingdoms - S8-E2
Continuity mistake: During the battle strategy meeting around the table, Sansa wears the long silver chain and circle neckwear, and the long chain changes the way it is placed through the circle. Sansa's chain is put through the circle in a way that's over and under in most shots, but when Jon explains that if the dragons are in the field they won't be able to protect Bran, the long chain is put through the circle the opposite way, under and over. (00:30:05)
A Knight of the Seven Kingdoms - S8-E2
Continuity mistake: When Gendry gives Arya the dragonglass weapon that he made for her, in the following shots Gendry's leather cloak straps switch between being crossed with his left strap over the right strap, or his right strap over the left strap. (00:43:00)
Answer: Basically it's because he broke his vow. A member of the Kingsguard is sworn to protect the king at all costs. Jaime elaborates more on the deed to both Catelyn Stark and Brienne of Tarth, telling Catelyn that no matter what course of action he took, he would be breaking one vow or another (i.e. if he obeyed the king, he would conversely be disobeying his own father), and telling Brienne that the Mad King was planning on burning all of King's Landing, but he did not bother to tell Ned Stark that. Ned Stark felt that killing Aerys was dishonorable and excessive. Robert Baratheon still could have usurped the throne without Aerys being killed.
Phaneron ★