Locke's concept of faith is greatly examined in this episode. The dichotomy between faith and science is another one of those basic building blocks of the whole series. Locke trusts that a higher power gave him back the use of his legs, and the power is somehow tied to the island. He has no rational basis for this assumption, save that his legs do work and there is no rational explanation. When his faith is tested by his failure to open the hatch, he begins to lose feeling in his legs.
There are several moments in Locke's flashbacks over the first couple of seasons where we are teased into thinking that particular incident is what caused him to originally lose the use of his legs. Getting hit by a car is the first of these teases.
We find out much later that Locke's mothers belief in John's special nature is due partly to Richard Alpert's intervention when Locke was a child. Alpert was extremely long lived and was directed by Jacob to visit Locke in his childhood to determine if he was a candidate.
Locke's vision of the Beechcraft airplane crashing in the jungle was of course a real event on the island. They stumble upon the wreckage of the old plane in the next episode The plane itself was carrying Mr. Eko's brother and a load of drugs and crashed on the island several years prior. We will meet Mr. Eko next season.
It's kind of a shame we never got a flashback from Boone of his nanny, Theresa. But Boone doesn't last much longer anyway. So we never get to see exactly how she falls up the stairs. Too bad.
Locke's father turns out to be the "Sawyer" that our Sawyer is searching for, who brought about the death of his parents. This may be the most toxic cross-character relationship on the show.
Boone again says "we got to go back" when trying to help Locke walk.
Anthony Cooper tells Locke, "See you on the other side, son." This is fairly similar to Desmond's farewell to Jack, "see you in another life, brother." At first I thought it might be significant, but it's such a common phrase it probably is not.
The subplot about Sawyer needing glasses kind of slipped my mind, mostly because once he gets the glasses they don't last that long. He doesn't wear them very much in the future. But then, there's not as much time to sit and read so it would make sense.
Though Locke and Boone don't realize it, they and the Beechcraft or very close to another hatch: the Pearl station. It will be discovered a couple seasons later.
Boone makes contact with Bernard and the Tailies over the plane's radio. In an episode next season, we'll see Bernard receive Boone's transmission in a flashback. At the time, I remember wondering if there was some sort of parallel universe/time travel involved and they were talking to themselves. I guess they were in a way.
Locke's life to this point has been a pattern of faith and betrayal, faith and betrayal. It's amazing that he's kept at it. But eventually his fate will be rewarded when he sees the light in the hatch.