Locke's wheelchair makes its first appearance.
Now that Jack in Hurley know that Kate is wanted by the law, we're not quite as sure if she's a good guy. We see in the flashback that she's on the run, in Australia, but we don't know any details of what she did. Jack doesn't seem to care but it freaks Hurley out.
First use of one of The Numbers: Kate's reward is $23,000.
Walt seems to make it stop raining instantly. While we do know he does have some powers, this is more in line with what he can do. There's a webisode from much later in the series that shows what Walt could do when he was in custody of The Others.
There are a number of two-person relationships that for me between all of the cast. The one that forms between Locke and Charlie is one of the most profound.
In a repeat of cakes airplane flashback once again we see the poor woman fly up and slam to the ceiling of the cabin for about the third or fourth time. I think it's high time someone wrote some fanfiction about that character. We also once again see the bag from the overhead compartment nail the Marshall in the head. That I could go without seeing again. The effect of the tail section breaking off and falling away for the plane is an awesome effect. I also would hate to be one of those guys that get sucked out, especially the one who didn't have his seatbelt fastened. How embarrassing.
With Sawyer realizes he screwed up in killing the Air Marshall with one shot, it's a very rare look of contrition on his face. Throughout the series he's supremely confident, self-assured and unapologetic. But this is a rare time when he realizes he really messed things up.
The Air Marshal is the first actual character with lines to die on screen.
Jack says that three days ago they all die. What he means is that their past lives no longer matter and they have a blank slate. What actually happens is that this begins a multi year argument I'm on fans that they all indeed died, and the island is the kind of purgatory. In the end, this turns out to be more true than not.
The very end of the episode features an element common to the first season, and ending musical montage. This one is all about reconciliation and connections. These musical montage is eventually go away as the second and third seasons come around. The same pattern happens in The Walking Dead as well.
We also see a rare fade to black.