The Russian Avto-23 Heavy Crane has a strange bug in co-op. On the player's screen, the crane appears normal. On any other client's screen, the crane is flailing about at light speed, warping the truck model. This appears to be a physics and/or network problem tied only to the Avto-23. The US heavy crane doesn't display the same problem, nor do either of the light cranes.
This also destroyed the ground, but only for my buddy. He's describing the ditches left by my crane on his client as "anti-tank ditches." It also caused a lot of floating rocks. None of this terrain deformation is visible on my end.
First screenshot is from my perspective, second from my friend, taken at the same time.