It's entirely possible he's realized all this now, after the fact, and that's why he's drinking so hard by the Craphole Island campfire. He polishes off one bottle and tosses the empty on the sand, almost hitting an approaching Locke. "So what did one snowman say to the other snowman?" asks Locke, and Desmond, pulling the cork on another bottle, like just how much booze does this guy have, says, "Smells like carrots!" And Locke smiles like it's really funny. Desmond passes over the bottle so Locke can take a swig. Desmond asks if Locke fixed the computer. "World's still here, isn't it?" says Locke, but Desmond ain't so sure, maybe because he CAN'T SEEM TO FIND IT AGAIN. Locke wants to know what Desmond would say if Locke told him that the three years he spent pushing the button, and all the years men before him did the same, was all for nothing. "I'd ask you, 'How the hell'd you know something like that?'" says Desmond, heavily slurring his words. Locke explains about the film he watched in Pearl station. Desmond stares at him. "You're lying," he says. Locke takes the Pearl station tape out of his backpack and gives it to him. "You want to take a walk? I'll make the popcorn." Aw, he finally got up the courage to ask Desmond out! Desmond angrily says that if Locke thinks it's not real, then he should stop pushing it. "Well, I have, except unfortunately, someone else decided to start." And he leans forward suddenly, and gets up in Desmond's business, and tells him to sober up, because they're going to get a good night's sleep and then go find out what happens if the button doesn't get pushed. Note: Desmond does not explain to Locke that HE ALREADY KNOWS what happens.
Elsewhere, by another fire, Sawyer offers Hurley a "Dharma Nutrabar." As appealing as that sounds, Hurley turns it down, saying he's not hungry. "You serious?" says Sawyer, who couldn't be nice for five seconds without making a crack about Hurley's weight.
Michael's over in the trees having another conscience attack, and Jack strolls up to ask if he's okay. Mike makes up a lie about getting more firewood, but not feelin' so hot. Jack says he shouldn't be out there on his own, and offers to help. Michael thanks him for coming out and risking his neck for Walt, I'm guessing to try to allay some of Jack's obvious suspicion. "Hey, live together, die alone," says Jack, who ought to put that on business cards by this point. Michael nods, and then stands around looking guilty.