I looked thru out this forum and I have not seen this as a headline so excuse me if its a duplicate. But my last defeat when my island got attacked five hours ago a santa died and my cannon kept shooting its bones and my ground pounder did too. Until they got destroyed. They never readjusted themself on another target.
It had been a bug from the past but I hadn't heard of it resurfacing. Look to see if it happens during any attacks too or just replays. It could be a replay only bug. If it happens frequently send a message to rovio support or tag Sir Bugsalot in a post.