Battlefield 2 via CrossOver: Graphic Bug With High Terrain
Unlike on a Windows gaming machine you don't have many choices to fix such issues on a Mac. As far as I know there are no dedicated drivers sections on the NVIDIA or ATI pages and no possible beta-drivers from Apple.

After a couple of years I ended up with a separate Bootcamp partition for the gaming fun because (forgive the harsh words) all the CrossOver, Wine, whatever crap sucks! Take a look in the AppStore and see the comments on Civ V as an example. Even the relatively smooth running and still good looking Eve Online has some glitches.

Sorry for the negative mood, but I think we'll have to wait some more years to see more 'native' mainstream games like Starcraft.