When the Addamses receive a letter from Professor Simms the genealogist, Morticia's necklace changes from a small clear stone to her signature larger black stone.
When the mailman arrives, Thing takes two letters from him. He only passes one letter on to Wednesday. (This is due to the mailman's scene being reused footage from The Addams Family Goes to School (1964).)
Pugsley hands over a box containing a tarantula to Morticia twice.
At 2:24 Morticia and Gomez are helping Pugsly wrap a present. Placing his cigar in his mouth, Gomez bends down to help. Morticia stops him claiming he's "all thumbs" (meaning: lacking manual dexterity). Gomez stands up, eyes glinting, staring at the palms of his hands "Wouldn't that be interesting?" Studying his hands he slowly turns them over completely forgetting about the cigar. A consummate actor, John Astin flinches when his left thumb hits the cherry of his cigar. There is scorch of ash on his left thumb at approximately 2:32. Even though there are some editing points John Astin can be seen furtively glancing at his injury and while continuing the scenes. REVEALING MISTAKE: Gomez wasn't supposed to burn his thumb revealing how actors can embody their characters so completely they aren't aware they are about to hurt themselves.