Both of these issues are known in the firearms training community. When I took the SigArms Instructor class a couple years ago one of the instructors said he never believe that a dropped round could go off until it happened during a class he was teaching. (I forget the exact details as to why the round was dropped).
As to empty cases going back in backwards, that one I've seen myself. It was at an indoro range and the shell hit the divider and flipped back into the gun, backwards. The student was shooting my Glock 19 when it happened. I didn't have a camera, so no pics, sorry.