I scouted through to make sure that no one's said it yet, but I found a bug in multiplayer!
My friend and I are both in frontline, for one. We're on the guardian's fight (with the hydras) and for some reason my internet isn't working so well. If I reconnect in the middle of my friend having started the fight, we get some... er... interesting results. I don't know if it's something to be reported here or elsewhere but it, I guess, would count as out of bounds? Since for a while I am out of bounds.
I was taking a lot of screenshots because I thought it was hilarious but that also makes for excellent documentation, right?
There are a few others I have. The fight starts me off in winter like I just entered the temple normally, and that lets me walk out onto the water. Usually the gates aren't up at first so if I want, I can OOB the gated off areas too. The music and sound effects try to keep up but after a while, it actually starts back over like I just started the fight myself. It's really weird.