Throughout the episode, Wednesday's hairstyle changes - sometimes multiple times in a single scene - from braids to a double-ponytail style held with multiple bands and back.
When Uncle Fester puts the bulb in his mouth the second time, it is pointed straight out. In the next shot, it is angled to the right.
In this episode we learn Wednesday is 6 and Pugsley is 8. In just the next episode, Morticia and the Psychiatrist (1964), Pugsley is 10.
When Wednesday holds up her doll Marie Antoinette, it changes hands and turns around between shots.
Thing pulls two envelopes out of the mail-carrier's hand, yet later when Wednesday takes the mail from Thing, there is only one envelope.
Towards the end of the show when Thing hands the phone to Morticia, you can see Ted Cassidy's foot scoot behind a chair as Gomez passes.
Control-wire visible for upper gate-latch as Charlie passes through it.
The bear rug doesn't roar every time it is stepped on.