I exited this cave on the edge of water, very near a water fall, a few times. Each time the animation would do this weird thing where I would exit out the back of the cave, then loop around the right side where the water was, and walk around the front of the cave, and at that point I'd gain control of my character again. A few times I did this, and then I was kidnapped by a giant bird, got the egg to hatch, and the exit cave was that same cave on the water's edge near the water fall. When I exited it, the Robin was with me, and I got bumped onto the clouds and couldn't figure out how to get back onto land.
Exit a cave very near the water's edge with a Ro Bin in tow where the cave is also is very near a waterfall, maybe? My guess is the Robin is knocking me off the edge of the map.