Not all revives are made equal, as players have recently discovered while running rampant through the new Oasis map. Off near its gardens, if Mercy revives you after you've fallen off to your death, you end up underneath the map itself.
Which is where the trouble actually starts for the enemy team. You're free to shoot through the floor, use your abilities, use your ultimate... and, ultimately, risk getting banned for abusing an exploit, as Kaplan and company aren't exactly happy when players abuse things they're blatantly not supposed to be able to do.
Good news: it's getting fixed. Said Principle Level Designer Dave Adams:
There is an incoming fix for this and the area under the bridge in Eichenwalde.
Of course, if the enemy Reinhardt's the one that knocked you off in the first place, and then Mercy revives you, it's not your fault you're stuck there, right?
(PVP Live does not condone the abuse of in-game exploits.)