Locke inspects the glass, in vain. "This was supposed to work," he says, then gets up and stomps, and yells it again. Yeah, this'll work. Boone yells over for Locke to look at his leg. Locke looks down, and sees a six-inch shard of metal buried halfway into his leg, which came from I know not where. I mean, I know it's supposed to have come from the metal thing on the trebuchet, but it's buried in his right leg, and Locke was standing to the right of the trebuchet, so the shard must have boomeranged around before shooting straight into his leg. Locke seems as surprised as I am about the shard, and reaches down to pull it out, not displaying any pain. "You okay?" asks Boone. Again, Locke seems mildly surprised, and says he's fine.
That night, alone by a fire, Locke's got his leg bandaged up. He takes a safety pin and jabs it in various places. Nothing. He tries the other leg. Nada. He looks distressed, and takes up a burning stick from the fire, and holds it to his sole. We hear the flesh sizzle, but it doesn't affect him at all. John Turturro shows up, and stabs Locke's foot with a fire poker. Still nothing! I'd be thinking, "Cool!" only I imagine Locke's kinda worried he's going to lose the use of his legs again.
Back from commercial, Boone and Locke are building another, hopefully stronger trebuchet, despite Boone's skepticism that the glass will break. Locke says everything breaks if you apply enough force. Boone's all, well, what if it doesn't? "Then the island will tell us what to do," says Locke, prompting an "exsqueeze me?" from Boone. Locke doesn't repeat it, and says instead that Boone should salvage the other pieces from the first trebuchet. He struggles to get to his feet, prompting another "Are you okay?" from Boone, and Locke tells him he's fine. At this point, can I just point out how odd it is that no one else on the island has stumbled upon this thing? No one's followed them, to nose around? Not even Kate?