 As Homer arrives , a helicopter lowers a small but powerful bomb down a rope through a hole in the dome , set to go off after 15 minutes . Homer goes down the rope , knocking the escaping townspeople and bomb off of it which gets him booed away . After reconciling with Bart , Homer drives a motorcycle along the dome , inspired by the earlier carnival attraction . As a passenger of the motorcycle , Bart throws the bomb through the hole ; seconds later it detonates , shattering the dome and freeing the town . Cargill prepares to shoot Homer and Bart , but Maggie knocks him out with a boulder . The town praises Homer , who rides into the sunset with Marge and Maggie , whereupon the townspeople restore Springfield to normal . As a symbol of their gratitude , the Simpsons and their friends begin to rebuild the family 's house . 
