It wouldn't be a problem for any other show, but since South Park is typically submitted to Comedy Central the day of airing, a silly little thing like a blackout can cause an episode not to air:
On Tuesday night, South Park Studios lost power. From animation to rendering to editing and sound, all of our computers were down for hours and we were unable to finish episode 1704 "Goth Kids 3: Dawn of the Posers" in time for air tonight. Trey Parker said, "It sucks to miss an air date but after all these years of tempting fate by delivering the show last minute, I guess it was bound to happen."
GOTH KIDS 3: DAWN OF THE POSERS will air next Wednesday, October 23rd. Tonight there will be encore, Live-Tweeted presentation of Scott Tenorman Must Die at 10p EST.
Via South Park Studios