If you control Kalitas, Traitor of Ghet, you get a Zombie token when a creature you control owned by an opponent dies
When I cast Crux of Fate to kill all creatures Kalitas exiled the Birds of Paradise I owned that they controlled, when Kalitas specifies it only triggers on creatures of my controlling dying. The Zombie Token resulting from this trigger was then able to attack and kill a planeswalker next turn when that zombie shouldn't have been in play
Yes this exact bug happened to me as well. My opponent stole my Kroxa with Agent of Treachery. When I killed my Kroxa that I owned but did not control with Kalitas on my opponent's battlefield, my Kroxa was exiled and they got a zombie token when that should not have happened.
I stole my opponent's Kalitas, Traitor of Ghet with Dragonlord Silumgar. When my opponent killed Kalitas, it exiled itself and I got a zombie token.
This also just happened to me. My opponent controlled one of my creatures. I killed the creature which I Owned but he Controlled, and the opponent received a zombie token and my Owned creature (their Control at the time) was exiled instead of going to my graveyard.
1. Opponent used Control Magic to gain control of my Merfolk Looter.
2. I cast Reanimate on Opponent's Massacre Wurm while Opponent had their Kalitas, Traitor of Ghet in play, killing the Merfolk Looter with the ETB trigger.
3. Merfolk Looter was exiled instead of being put into my graveyard.
4. Opponent received a Zombie token.
1. Opponent used Bribery to play Kalitas that I own
2. I killed kalitas with a removal spell
3. Kalitas triggered on itself and created a zombie for my opponent which shouldnt be the case