I’m not really sure what to call it, or what to search for, but I’ve been periodically finding SpringConstraints seemingly stretched halfway across the map of RoCitizens.
It appears that sometimes the wheels of unmoving cars (connected via CylindricalConstraints and SpringConstraints) get separated from the body, but only graphically. There’s no collision and the frame still sits propped up as if the wheels were on.
It happens rarely and I haven’t been able to reproduce it yet myself, but when I’ve seen it happen, I’ve noticed that if the frame is bumped by a person or a rolling car, the wheels will automatically realign to the correct position.