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)
Answer: This is explained more in the book. Khal Drogo and his bloodriders do intend to help Viserys take the throne, however they do things in their own time. This is what causes Viserys's frustration. In the book, Illyrio Mopatis tells Viserys that he has already waited his entire life to claim The Iron Throne and that waiting a few more years isn't that big of a deal. The Dothraki are a nomadic tribe, which is largely why they have no interest in invading and sacking King's Landing. However, since Khal Drogo eventually grows to love Dany, her assassination attempt by the Westerosi compels him to seek revenge.
Phaneron ★