Okay so I opened the clown car today. The results were quite odd.
My map has two candy canes. I opened the one on the left, got the usual message, but the clowns spawned under the other candy cane for some reason. Most of them then proceeded to wander the circus aimlessly rather than heading up into the trap I had prepared for them. There was a perfectly open (albeit long) path available to them, and my miner followed it no problem.
Reloaded previous save.
This time I opened the cane on the right they and appeared again, still under the cane on the right. So far so good. My miner heads off to get a drink, again using the prepared path. The clowns follow briefly, but stop after about 30 steps. After awhile of waiting for them to move I notice there is less of them than there used to be. They've gone back down the cane. Then the strangest part, they're in the magma sea. The only open holes to the magma sea are under my magma forges, with the non-walkable tiles covering the holes. At no point do the spires open into the sea, so they could only have gotten in by teleporting through a wall. They aren't even trying to get in through the forges, they're just scattering in all directions, including up/down.
My brilliant trap would appear to be worthless as it relies on the clowns actually wanting to get into my fort and tear it apart, and the teleporting means I can't even send the military after them.
Can anyone enlighten me as to what the hell is happening here?