1) Jorah doesn't get greyscale in the books — somebody else does
(HBO)
The core of this week's action sequence involving Tyrion and Jorah is drawn from
A Dance With Dragons. In it, Tyrion gets attacked by the "stone men" while on a riverboat journey through ancient ruins — but on the page, Jorah isn't there.
Book Tyrion takes this treacherous voyage before his kidnapping by Jorah. Instead, at this point he's still traveling with the characters Griff and Young Griff, who
seem to have been cut from the show. It is Griff who saves Tyrion from the water, and is later revealed to have contracted greyscale in doing so. Though Jorah doesn't have an easy time of it in book five, he appears to be disease-free at the very least.
The setting is also different — in the books, the stone men don't live in the ruins of Old Valyria. Indeed, it’s said no one has ever visited that mysterious locale and returned. Instead, the stone men inhabit the ruined city of Chroyane in a part of the Rhoyne River known as the Sorrows.
Finally, book Tyrion doesn’t see Drogon flying overhead — not clearly, at least. In the fog, he briefly spots "a half-seen shape" above him with "pale leathery wings," but it disappears before he can get a better look.