I have fallen off the map a couple of times in the Bixie hive. Seem to happen always around the same spot, near the queen bee.
I found out that if you run far enough away from the instance once under the map, you eventually "pop" back at the beginning without losing a life. It actually saved me a couple of times, falling when I had almost no life left and popping back at the beginning fully recharged and ready to fight
