Following up the amazing gallery of stills from the production, Entertainment Weekly now has a new report by Jennifer Armstrong with some details. There’s a reference to a “pivotal scene” being moved from Catelyn’s bedchamber to a meeting place, which we suppose means they’ve moved her receiving a certain message to the scene corresponding to her first chapter. If true, this is a rather interesting change, immediately introducing the main mystery of the first several novels.
Also, Jason Momoa is apparently naked more often than he talks (hah) and there’s references made to unicorns (which do exist in the setting, but probably aren’t anything like you imagine!)
Here’s the opening paragraph, clearly describing the scene in the godswood. I actually saw the heart tree’s face in the prop room at Belfast, but it was in fact from the pilot and they had redone it for the reshoots: