Originally Posted by v2micca
I suspect one of the big "butterfly effect" issues is the killing of Mago in the first season. From his interviews, GRRM has indicated that Mago would play a significant role in the upcoming 6th novel. It will be interesting to see how the show runners work around that plot point.
Martin himself wrote the script for the season one episode "the pointy end", in which Drogo kills Mago. If he didn't want him dead, maybe he shouldn't have killed him.