make your static models/entitys poly precise for collision.

moving entitis should not use it ( untill octree culling eventualy), defualt now moving entities use a elipsoid collision hull. ( remember even with the poly collision the engine is still for now a BSP engine nd still has 'some' of teh limitations of a BSP engine, but not all)

watch your models animations, incase in its aniamation frames it moves its mesh outside the defualt collision hull area ( the models collision hull is set based on the BASE (first) model frame of the entire model)

you may need to manualy increase its hull size to compinsate for animations excedding the hull