In the close-up of the turtle with hair growing on the heads, the edge of the piece of wig is visible on the left head (audience's right).
After Fester appears during Mrs. Dragwater's visit, her reaction shot is noticeably more grainy and lower quality than the footage before and after. This is because this close-up was created by blowing up part of the preceding two-shot.
(at around 13 mins) Just after the cracked mirror falls, you can see the outline of the crew member's two fingers poking through the canvas wall in a second, unnecessary, attempt to get the mirror to fall.
When the guy delivering the package asks Lurch to sign for it at the front door he pulls out a #2 pencil from his ear to use but a signature would need to be in ink not pencil. Fortunately when he gets inside Thing signs for the package with his own quill pen.