Continuity mistake: When Fester tries to access the vault alone for the first time and is grabbed by the chain, he has wearing a vest of things like dynamite. When he exits the chute it's gone.
Continuity mistake: While eating with the family, Wednesday's left arm is on the table while she looks to the right. A shot later she is staring down at her food and her arm is lowered. (00:41:52)
Continuity mistake: When Pugsley asks Fester if he likes the blood, his left arm swaps between being under the table to being on the table. (00:57:39)
Answer: No doubt the Addams house had one of many secret, confusing passageways to get to the higher floors (and other parts of the house) from the vault that the viewer obviously is not privy to.
Scott215
It made me confused that if there's another secret way up to the house other than the slides or the bookshelf even though Fester had trouble finding which chains to pull but couldn't find the right one, If there was another way into or out of the vault and that means Fester had to know there was if Gomez was with him than Fester would have try the other one too instead of the bookshelf.
Trainman