In the first movie, Abigail and "Gordon" are supposed to be master con artists, the latter shown extremely competent at any number of illegal activities. But neither of them thought to put paint on their palms to mark the rungs they were grabbing so that they could eliminate them and eventually find the right one?
1977's Halloween With The New Addams Family introduced two new children, Wednesday Jr. and Pugsley Jr., who were never heard from again afterwards. Seen in the light of the Addams traditions from the second movie (i.e. when a new baby enters the household, one of the children has to die) - well, that's a nasty possibility, isn't it?
The children in the hospital are probably traumatized for life after hearing Wednesday's parents "had sex".
How is telling a child that two adults had sex horrifying? It's not like they pulled out some porn magazines. Then again, different people have different views on this.
