(Adapted and extended from this comment.)
According to this link, the rapture will roll around the world like New Year's, occurring at 6:00pm local time in every time zone on May 21.
6:00 at UTC+12—the International Date Line—is 10pm tonight Eastern Daylight Time.
This raises several thoughts:
First, if the rapture starts at the International Date Line at 11pm Eastern, the news of mass disappearances would make its way to us by the time we woke up on Saturday... giving us Americans (who would be among the last to be raptured) plenty of time to repent and get raptured up.
This is, of course, just more proof that God loves America most, placing the International Date Line where He placed it. It'll give more Americans a chance to repent and be raptured, so we'd have a majority bloc in Heaven.
Even more significant is that among the last places to go, meaning the most repentant souls, is Alaska, at UTC-9—one of the last heavily-populated places (aside from the Hawaiian Islands, UTC-10) to be raptured up.
Meaning that the entire population of Wasilla will be in Heaven.
Second, the rolling 6pm rapture brings up many interesting questions relating to time zones.
(A) Will the rapture go according to standard or daylight savings time? If it's DST, then we get it at 6pm in our own time zones. But if God doesn't respect Daylight Savings Time, then it'll be at 5pm, and all the folks who thought they had until 6pm to repent will be SOL. There are arguments, I think, for and against God respecting Daylight Savings Time. On the one hand, it was invented by Benjamin Franklin, who was a deist—not a Christian. But on the other hand, it was a Republican Congress who approved the extension of DST in the 2005 energy bill, and we all know that God is a Republican.
(B) The DST question raises another interesting quandary: If God does observe DST, then, do Arizonans (whose state doesn't observe DST) get raptured along with their neighbors in Colorado and New Mexico on Mountain Daylight Time, or do they have to stick around for another hour to keep the 6pm local time thing and get raptured with the Californians?
(C) Yet another odd question: Newfoundland is UTC-3:30—so do they get raptured at 5:30 with the Atlantic Time people, or at their own 6:00—which would be 5:30 for their neighbors just to the south?
(D) If I stood on the Illinois side of the Illinois/Indiana border (a land border between Eastern and Central time), could I watch folks in Indiana getting raptured and still have an hour to upload the rapture video to YouTube before I do a quickie repentance and take the plunge myself?
(E) What if I were to straddle the Illinois/Indiana border at 6:00 Indiana time? Would half of my body be raptured, and the other half remain on earth?
(F) If a fundamentalist Christian minister is driving east from Illinois to Indiana and crosses the border sometime between 6:00 and 7:00 Indiana time—meaning he missed the rapture in Indiana, but got out of Illinois before the rapture started there—is he SOL, or does God take him up as he crosses into Indiana?
Just some things to think about...