Revealing mistake: When Carla and Elliot are walking through the graveyard, Elliot falls into an open grave. After she has fallen off the bottom of the screen, you can see her ankle flick up in the bottom of the picture, showing that she actually just fell down on the floor during shooting.
Continuity mistake: After Elliott falls into the grave, she tries to pull herself out by placing both hands on the edge of the grave and jumping. When she falls back in again, there are two clumps of dirt missing from the edge where her hands were. In later shots, the edge of the grave is unmarked.