Errol Childress from his house, to his speech, to his "making flowers" with that old lady. to him painting at the school--the guy just radiated creepy from his pores.
Then the showdown in "Carcosa," with fantastic set-design and atmosphere, in which you for sure thought they were both going to die. Not to mention that hallucination (or was it?) Rust had before Childress stabbed him.
At first, I was a little curious about there were things that didn't seem resolved, such as the situation with Marty's daughter, but then, looking back, what's important isn't so much what the cause was but that Marty wasn't paying attention to his family like he should've been. And, of course, that hits Marty like a wave when he's in the hospital and the family he had so taken for granted and ultimately pushed away actually came to see him.
And of course, the final scene between Ruse and Marty, and, just like they've done all through the series, just stellar, Emmy-Award worthy performances by Harrelson and especially McConaughey. Having the pessimistic, embittered Rust have such an emotional breakdown full of both joy and sorrow over his near-death experience and his daughter was just such a great and fitting way to end his whole arc, and I confess I found myself rather moved. And I especially loved the "Light vs. Dark" dialogue, especially how it's the "only story" and, even though how Marty says, looking at the night sky, that it looks like the "darkness outnumbers the light," Rust tells him he's looking at wrong, "Once there was only dark. If you ask me, the light’s winning"