When Thing is holding Morticia's palette, he is a left hand instead of his usual right.
In the opening shot of Cousin Itt doing his magic act, Felix Silla is not wearing the bottom truss of Itt's hair and his legs are visible.
The steam coming out of Gomez's ears are actually coming from behind his head, although in on the televisions of the time this may not have been noticeable.
Lurch's fingers are not pressing the keys of the harpsichord in time with the notes heard.