Plot hole: Laura says she knows it's Sam's car in the accident because she recognised the registration number, but the car was angled down too deeply; there's no way she could have seen it.
Plot hole: When Rosemary discovers the side door to the church and a plastic knock, from an arrow, on the floor, she jumps to the conclusion that the arrow was shot from the side door. This all makes sense - this knowledge is how they catch Mr Danvers - but there are too many branches from the Yew tree to make this possible.
Answer: Regents park.