Never had any major mishaps myself.
Once I had removed the towball to install a shinguard. Did it up tight. Was driving around with a tandem car trailer (Nothing on it) for about quarter an hour. Decided to check the towball. Glad I did, the nut was halfway down the threaded shank. Did it up as tight as I could kicking an adjustable spanner, drove slooooowly home and then did it up to FT (F'n tight).
Another time, doing service for my mate's 89 RS Legacy in the tag-along for the NZ WRC.
We, uh, had to go rescue the RS cos it had broken for the millionth time. However my car was already full. Didn't stop us did it.
We were using my 2000 Outback (a 6 thankfully), I had it stacked to the gills with service crew and gear, towing the 1500kg rally car, on a tandem trailer, with the driver and co-driver sitting as low in the rallycar as they could so as to avoid being seen. Drove like that for maybe 5 k's through 50 zones. Took an hour cos we all stopped for pies (day was shot anyway)
Oh, and I passed a cop like that too (Breath was held!)