I used the buggy furnace minecart to push a minecart into an endermite, and it flew off, and was hovering in midair with the endermite located just below it.
What I expected to happen was...:
I expected the endermite to sit in the bottom of the minecart on the ground, and the nearby endermen to come close but not be able to hurt it. I was testing enderman magnets.
What actually happened was...:
The cart did not reach the ground. When I flew away for a while and came back, the cart was on the ground and the endermite nowhere to be seen. Maybe it despawned midair and the minecart then was able to fall?
Steps to Reproduce:
1. make a track, a loop, in the air, 8*2, on polished andisite, only normal rail, facing north to south
2. Put on one of those furnace minecarts with a normal minecart either side (near the end) and spawn some endermites on the track either side
3. put a coal in the furnace minecart
the minecart on one end(idk which i cant tell so i put it on both sides) will fly off.
I tested this myself, you don't need a furnace minecart, just push it off. Seems to work with west/east as well