When Homer tells his family the Rapture is coming in half an hour, he turns on a light switch outside a bedroom. When Maggie blows out her candle, the hall goes dark. Yet no one turns the hall light off.
In Krusty's live "Celebrity Salute to Specials", 'Clown' is spelled 'Klown'.
When Homer is calculating the date the rapture will occur, one of the numbers he uses is 666, presumably in reference to "The number of the Beast", but the Number of the Beast is actually 616, not 666