Episode spoilers: So did the Mountain die at the end? Oberyn did get him pretty good beforehand, and he did kind of collapse right at the end.
Well they declared
the Mountain the winner, so that should answer that question. As for the books...
the Mountain does survive for a while but succumbs to the poison from Oberyn's spear which was very painful and slow. Maybe they just don't feel like spending the money on it.
Loved the fight, but the episode's highlight was Sophie Turner's acting. And Sophie Tuner in that dress later on. And the potential story ramifications of Sansa being out in the open at the Eyrie.
This is one of the cases where the show has improved on the books. I think in general the show has handled the female characters better than the books.