Other mistake: When the family visits Assimilation, they come upon the Chipper and Cheer practice. When Margaux arrives, she greets the family by saying, "Well good morning, neighbour!" However, Margaux had earlier told Parker that the practice was in the afternoon.
Other mistake: After days, when the evil Margaux sends messages through the neighbourhood app to warn everyone about the Addams allegedly about to "attack the town", on screen you see that there have been no new messages since the first time she used it, during Wednesday's arrival at school. Would be quite strange if days went by without a single new message. (01:03:40)
Other mistake: Not to dispute cartoonish antics, but in the climax of the movie, Pugsley's bombs destroy the boulders fired by the catapult without causing as much as a little bit of dust, while the house crumbles with a lot of detail in rubble, falling bits and assorted devastation. The whole explosion effects look really like they don't belong with the rest of the mise-en-scene. (01:11:30)
Factual error: Parker is looking for the phone her mom hid. She is moving a box of cereals. The cereal ingredient label has a few joke entries you may Miss at first (goat hair, bitter almond paste, false eyelashes), but the nutrition facts tab is also incoherent in a way too subtle to be a deliberate joke; sub-categories of each macronutrients exceed the total. For instance, it has 5 g of Fat in total, but 25 g of Cholesterol and 56 g of Saturated fat (at most it could be mg). (01:00:25)
Other mistake: The villagers cut the Addams' escape path demolishing the bridge using a flaming projectile from a catapult. Gomez looked towards the bridge (and we as audience got a clean view too) and there was nobody in sight; how did not just a small crowd but also a large mechanical weapon materialize so suddenly? With a fire that would have cast a light in the dark, even. (00:03:30)