Wierdest thing I've seen was in the first version of the Trinity terrain, pulling one of the freewheeling 90mph downhill runs in a Panzer IV, and I made a course correction so that I wouldn't hit the bottom square and bounce my tank high enough to overturn. Of course, I overcontrol at that speed, and my tank starts to roll -- right[/u] as it hits the polygon joint.
I will never understand how I managed to do it, but my tank did two complete rolls in mid-air, landed upright, and kept going. Unfortunately, I didn't have the presence of mind to be recording the run, and was laughing so hard after I landed the jump that I missed the next polygon break, hit it way too fast, rolled over, and died. I really wish I had film of that... it would be a real conversation-stopper.