Since the release of Overwatch, there haven't been many game-breaking bugs — especially not getting out of maps. And before you ask, no. I'm not talking about custom games.
On Overwatch's new map addition, Oasis, players are able to play underneath the map and hurt other players from below. Blizzard however, is already aware of the bug.
After suiciding off the side of Oasis, a friendly Mercy can come to your aid and resurrect you. When your character revives you'll be underneath the map. You'll have free reign to shoot to your hearts content and lay on the damage without the threat of death.
Dave Adams, Overwatch's Principal Level Designer, stated on the Battle.net forums that they're looking into the issue and plan on fixing it shortly.
Obviously we don't condone exploit abuse so if you see rockets spouting from the floor... you'll know who to report.
Gregory 'leeks' Ibanez once upon a time played Counter-Strike: Global Offensive semi-professionally under multiple organizations. He sticks to AWPing in CS because he's known around the office as literally the worst Widowmaker in Overwatch...