I did an RJ run today, and I have to say I like the new battle mechanics.
However, when the battle ended and the big pink guy exploded, a few minis were mysteriously left over. I'm guessing they might have been spawned by the polyps just as RJ was detonating.
http://steamcommunity.com/id/nicoya/screenshot/596951791321932936
http://steamcommunity.com/id/nicoya/screenshot/596951791321941295
Not a huge bug, but I figured I'd throw it out there.