Continuity mistake: While sitting on the couch, Peter suddenly has a clump of hair sticking up near the back of his left-sided part that disappears but reappears after some camera shifts. (00:01:20 - 00:01:42)
Revealing mistake: Although it appears that Edgar (and later Norman) put his eye up to the hole in the wall to look into the opposite room, the eye is obviously fake. Too much of the sclera (white part of the eye) is showing and the upper eyelid is too far above it; the upper eyelid typically reaches or partially covers the top of the iris (colored part of the eye). Also, the eyelashes go downward instead of being curved upward. (00:18:05 - 00:19:49)