it seems invulnerable to every single weapon, I first noticed this when I managed to bomb one with three gbu's in a mission and it just kept trucking. Further testing in the editor revealed that the only thing that would kill it is the explosion from a vehicle ramming into it, everything else seems to do nothing.
Update: Since the latest update it now is no longer invincible but now takes at least four GBUs to kill, might still need to be toned down since that's a lot of ordinance for just one hovercraft with little armor. Plus, now the ai on the guns for the ZUBR wont fire at enemies anymore, no matter the distance or if they're commanded to by the player. Only the right gunner seems to track the target, while the left gunner won't do anything.
The sound for it is bugged too, when you aren't accelerating it makes no noise. You only hear the engine whenever you accelerate. I also don't remember if it could travel on land before, but you aren't able to now.
And you still can't lock onto it using missiles, you're forced to get a lase on it and then lock onto that. It comes up on the sensor screen and you can target it, but all you ever get is the square brackets.