So the "Break the Internet" comment turned out to be exactly what every book reader knew it would be. Jon's death. But before anybody freaks out more, a couple facts that TV viewers can easily discover by reading news going around. A) Kit Harington was given a pay rise during the production of Season 5. B) He's signed a contract for seasons 6 & 7. Both of those should tell everybody that he's still going to be around in some form or another.
So now TV readers can join book readers in the speculation of how their "supposedly safe cannot be touched hero" is going to walk away from this cliffhanger.
The problem with TV compared to the book is that the book can show hints in the narrative. If TV tried to show those hints, it would give too much away, which is why they changed the Danaerys flashback scene in the House of the Undying all that time back. Because it would give too much away. Of course, they are trying to control things further by not telling the cast really what is going on, and making Kit Harington supposedly believe he is done, but the accountants are well aware of the situation... Of course, Kit Harington could also be deliberately telling half-truths to control the "rumours" himself, or at request of D&D -- He is actually dead, so he isn't lying.
The other problem with it is D&D once again not pulling the most important points from the book, and changing characters without really understanding their underlying motivations. They have really gone against the book in regards to Millisandre and her "predictions." None of the stuff she said to Jon remained present in the show, which just serves to turn the TV viewers even more against her. So many characters would be seen differently if they really understood them.
Of course, it's very possible that D&D will decide to keep Jon dead and completely change the ending of the story from what we
suspect GRRM intends... That would be the real break the internet moment...
Interesting how they didn't confirm Stannis's death. I'm almost certain Brienne didn't kill him, which leaves his story arc exactly how it ended in the book. Nobody has any idea of his fate.
I would say Myrcella's death was unexpected. But she is such an insignificant character in both the show and the books that it really had very little impact and just seemed a weak, unreasonable revenge plot device.
@willwallace is right about the new kingsguard, we've known this for awhile that they were doing some weird experiment with what remained of Gregor Clegane. I'm guessing what they've done is something similar to how white walkers came into existence.
I'm not sure that I approve of how they altered the walk of shame scene. It was almost entirely faithful to the book until they got right to the end and dulled down the moment she broke. In the books she covered herself and started running if I remember correctly, then collapsed outside the red keep, and was carried inside by Zombie Mountain. To me, if they'd done it the way it was in the book, it would have had much more impact and implication on where she will go from here.