I attacked and defeated StinkyPotato as a retaliation hit.
At some point in the second or so between landing the final hit and hitting "Hospitalize" my connection must've glitched and it appeared as though the button press never made it to Torn's servers, with the Hosp button stuck on the loading spinner that appears when the action is taken.
I hit refresh once or twice to no avail, and quickly disconnected and reconnected to my wifi. After refreshing the page again it appeared as though auto-leave kicked in.
I checked my event log to see if A) I was able to hospitalize him and B) how many treats I got for the attack, and found I received treats twice as shown in the above screenshot.
Looking at the attack log, it appears as though the hospitalization action never was registered:
However, upon looking at our faction's attack data via the API, it appears as though despite being a "leave" the retaliation bonus is still being applied: