Nothing serious, but I was fighting a dragon yesterday, and Mirri went down. I could tell because her health bar said DEAD. Okay, not a problem. It happens. But as I continued fighting, I got the prompt to use Blood Funnel. I wasn't in a group, so I thought, who is healing me? Turns out it was zombie Mirri. When the fight was over, zombie Mirri came running over to me. For a dead person, she looks pretty good.
Anyway, the problem cleared itself up when I ported to a wayshrine, but until I did that, dead Mirri continued to fight and talk to me.
One of those more humorous bugs.