User blog comment:AdventureTimeFacts/The GreatMushroom War/@comment-24856599-20140424235755

Good point there was no hole, but we can't rule out the fact that the comet could've been to small to make that hole. Also including that they didn't show the earth after the bomb went off. If you remember in the episode Finn The Human after the bomb went off there was no grass there only dirt so that could've been the hole..... maybe.