Basically the same as human ears naga but less noticeable i guess, idk if this has been reported still.
As I know he is from the Horde. Do you want him to have the symbol of the Alliance?
Technically, Cairne has the symbol before he joins the horde. It is wrong, but I doubt Blizzard would make a separate model just for two missions.
this are really acceptable bugs!
This can be considered an Easter Egg. That’s all.
Now, really, they are more important things to focus on War3 development!