In SP, Distant AI soldiers running down a steep slope do not always follow the visible terrain surface (angled slope), but about every 10m, they instead appear to run purely horizontally (away from the terrain), then fall down to meet the actual terrain surface (apparently injuring themselves in the process). After landing, they spin on the spot for a second before continuing running. It looks like they are running off the edge of invisible, large steps in the terrain.

Changing terrain detail and view distance settings does not make any noticable difference. When AI are within about 50m of the player, they always correctly follow the graphical terrain surface. {F18515}