Revealing mistake: When Mary of Guise is found dead by her nephew, he lies her down and puts his head on her chest. As he comes down, her eyes slap shut! If she were dead, they would remain open.
Revealing mistake: After Whale compliments Clayton for the marvellous shape of his head, Clayton pulls faces at himself in the side mirror of his pick-up before he drives off. Considering that the camera is positioned at hip level and we see his face in the mirror he couldn't actually see himself. (00:24:40)