The first eye-opener of the second season is Desmond, in the hatch, although we don't know who he is yet.
And Hurley mentions his Chicken Shack gets hit by a meteor. Or rather, meteorite. It sounds like a non sequitur what he mentions it, but we actually see it happen in a later episode flashback.
The conflicts and rivalry between Jack and Locke that defined itself in the previous episode really puts itself into action here. Jack is a man of science, medicine, and logic. Locke trusts in faith, fate, and the island to tell him what he needs to do. This division more or less defines the rest of the series, as far as these two are concerned. At various times they divide the survivors into two camps, each following one or the other of them.
The theme of miraculous healing works on and off the island. Even years before the crash, Jacob was watching Jack and manipulating