Plot hole: Just after Rita rescues Jeff, Diane's grave is seen close to where Jeff was buried alive. Even though Diane's been dead for several years, her make-shift grave site looks like it was freshly dug. There are no fallen leaves or other debris on top, no new vegetation (moss, grass, weeds, etc.) of any type growing on it, nor has the mound of dirt settled, shifted, or been affected by the weather.
Continuity mistake: While Rita is being held by Barney inside the cabin, she looks outside the open door and sees the mound of dirt where Jeff has been buried alive, just a few feet beyond the porch. When she escapes, she has to run a long ways through the brush to get to where Jeff is.