In UFO I really enjoy when you kill a Cyberdisc which explodes and kills other aliens nearby ... sometimes even other Cyberdiscs causing a chain reaction. It's a lot of fun and a great way for a soldier to get multiple kills with one shot as the game credits the soldier who killed the cyberdisc with the explosion kills as well.
Bio-Drones in TFTD don't credit the soldier with the kill though. If you check the save file they actually give the kill to the dying Bio-Drone rather than the soldier who killed the Bio-Drone. Anyone know if there is a reason for the difference or maybe it was an oversight?
Something else I observed with Bio-Drones (but might be true for Cyberdiscs as well): If you shoot a Bio-drone and it is knocked unconscious rather than killed, it still explodes. But then if a grenade goes off nearby, it will explode again! Is this strange or expected behavior? I was shocked that my grenade blast was so big until I figured out I was actually killing the unconscious Bio-Drone. Seems strange it can explode twice.