So I just went through BFD in Ashenvale and felt like it was very buggy. When i first entered there is a puddle I walked into and then walked backwards out of it but when i hit the edge i "Fell through the ground" or at least my camera did I had the keep pressing the walk keys around and it finally came back. My group said I was there the whole time though. Didn't seem like anyone else could repeat it but I did it 3 times and then couldn't repeat it / we began the raid.
Also when swimming around I noticed if i dove all the way to the bottom and touched the ground my breath bar would refill. It was almost as if my feet touched the ground I never ran out of air.