I always thought that you could modify a vulture's mine count with the hanger count trigger. Unless I did it wrong, I realize now I can't. Are there any other oddities like this one when it comes to ineffectively modifying hanger counts?

Nope, just vultures, you have to recreate them

None that I know of. What are you trying to do?

Using mine laying to trigger a spell. The mines won't do anything, it will just suck for the hero to need to be re-created if he wants to use his spell anymore than 3 times.