You have a normal collision above the Smoke collision, and it seems to be messing things up. I removed both and re-added just the smoke collision, and the simulation appeared to work flawlessly, no smoke came outside of the walls.
Before:
After:
I can replicate this issue by adding a stand...
Adding a collision and then a smoke collision messes up the smoke collision
@GiantCowFilms I'm working on rigging my cow for my short film . . . what a pain in the @&$# it is :P I have the eyes done so far, by far the easiest part. I am trying to figure out how to keep the feet rigged flat onto variable terrain. Any ideas?
@NoviceInDisguise That does work, just make one empty have the shrinkwrap, and then another with a floor constraint set to the first empty; then the second one will never go through the floor, and you can use it as the IK target