It's interesting when you think about it, Walt really has very little time that he spends with Michael before they're separated. A week or so in Sydney, and a month+ on the island. And then he was captured from the raft. After they escape there's time, but not before then.
The excavated outside of the hatch area looks very much like it did in the past, in Dharma times, when the hatch was actually being constructed.
The scene where Sawyer tells Jack about his encounter with his father is probably the closest the two of them ever get on the series. There's always a mutual respect, in some ways, although of course they're never close. Their rivalry over Kate and both characters' general stubbornness keeps them from being close allies. But it's good to know and see Sawyer has a bit of a heart.
Michael has a line he says to Jin, "No, this one goes here, that one goes there." This is a memorable line Han Solo says to Chewbacca in "The Empire Strikes Back." Only Star Wars geeks would probably get the reference, but there you go.
I never quite understood The Man in Black/Smoke Monster's reason for causing such commotion when moving through the jungle. It wasn't a large creature like he was pretending to be, so why the theatrics? Scare tactics? Intimidation? Probably, but after a while the effect is lost when you never see it. And intimidation and fear weren't quite what he wanted - just death.
Dr. Arzt had a chance to save himself when he left the group to return to the beach. The smoke monster chased him back, but in light of what eventually happens to him, he probably would have rather taken his chances.
The launching of the raft is one of the most triumphant moments certainly of this series, and of any series I've ever seen. The music especially is gorgeous. Knowing what happens to the raft and the people on it tempers the moment with heartbreak.