"I was just wondering is there some physical feature that makes the line of stones bend at that point?"

I haven't been there but I understand not. The juxtaposition between the line of stones and the "vanishing point" of Hartland Point (which, bear in mind, is the vanishing point for the whole Devon view) is very close. A couple of steps to the left and it's gone. On the other hand as you step to the right more and more of Devon becomes visible. So it's tempting to think that the cemetery was there because the deceased could still see the Homeland and the row was not so much pointing to Hartland as defining the boundary of the cemetery. It would be nice and human wouldn't it, wishing to be buried within view of the ancestral home? I'd quite like to be.