Seeing the grass flicker in and out of existence in the game, also there are patches of grass that are floating. This floating grass is bright red as if it's a debug feature. Also the formation for this red grass is that of a wall rather than on the ground.
EDIT - Neither the flickering nor red grass occur when any dynamic lighting is used, but as noted below, this has its own issues.
Other glitches with the game include shearing vertices when it's raining (exacerbated by lightning) and blurring in the sky-box when dynamic lighting is used (either objects or full).
EDIT - The shearing vertices seem only to occur when settings are changed in-game. I'm suspecting Anisotropics; when set to off, quit the game and relaunch.
This is running CrossOver Games 8.0 with Snow Leopard (Build 10A432), using the NVIDIA GeForce 9600M GT in my 2.93 GHz 17-inch MacBook Pro which has 4 GB of RAM.