Fantastic episode, although I seem to remember Oberyn being pummeled to death (rather than squashed) in the novel. Man, that was tough to watch.
I don't like how they're setting up the Hound's downfall. He's been a way more likable character in the show than in the novel, and we're seeing him go out with a whimper, ("gee, that looks infected, you should've let me burn it.") Still two more episodes left, but I've been somewhat disappointed at the way he's getting phased out so far. Maybe HBO isn't wanting to kill off another charismatic character so soon...
Something else I just realized: both Clegane brothers meet their "ends" from poison/infection, rather than directly in combat.