Stupidity: After Josh runs away from home after being turned into an adult, nothing seems to be done about his "disappearance." The only indication that he is missing is his picture on the back of a milk carton. There's no flyers about him missing. No mention of his disappearance in any newspapers or TV news about his mom saying that he's been "abducted" by a stranger. Even when Josh writes a letter home, he uses the actual address of where he's staying, but no cops turn up at his door after his mom receives the letter.
Stupidity: Barbara and Adam can obviously interact with physical objects (the statue horse, holding the door shut, etc.) but when trying to scare the Deetz's they tried visual stunts rather than throwing or moving objects.
Suggested correction: Barbara and Adam are not aggressive, intimidating people. Maybe they could have thrown and moved objects, but that would be almost violent. They would rather try a few visual stunts, instead of possibly hurting someone and/or damaging something in the house.
I respectively disagree with this. One of the visual tricks Barbara and Adam tried was her holding a bloody knife over his decapitated body, that in itself would have been violent and aggressive if they had been seen.
But they weren't violent and aggressive. They weren't threatening violence or aggression to anyone. They didn't commit an aggressive or violent act in front of anyone. They were just trying to scare them, just like wearing the sheets earlier.
Suggested correction: They first off didn't really understand how to interact with the physical world and secondly they didn't realise yet they were invisible.
I'm not sure the point of this correction because we see none of this is true. Barbara picks up a physical object and moves it without thinking about it. Then she looks at herself in the mirror with the horse and sees she doesn't have a reflection.
I have to agree. Even if Adam and Barbara couldn't be seen, the noose that Barbara "hanged" herself with or even the knife she was holding still should have been seen as they are physical objects and a knife, to the Deetz's, would be floating in midair and would probably scare them off.
Stupidity: Jack has been using Mosley's badge and identification to pass himself off as FBI. He never once uses this trick to commandeer a civilian car for him and John when it would have been the safest way to get to L.A. much sooner.
Suggested correction: Probably because If he did that, the car's owner like Red the bar owner would eventually call the FBI office to get their car back and then the feds would know the make, model, license plate, and the last location of Walsh and the Duke. The police would have caught them in minutes. Walsh had to keep a low profile.
Stupidity: Knowing that the Klowns' noses are their weak point from previously shooting them, Dave doesn't bother to shoot the giant Klown at the end with his pistol, instead waiting to be almost crushed and finally popping it with his badge pin.
Stupidity: John Candy was being dragged by the speedboat because he was holding the bar when the boat took off. It simply never occurred to him that letting go off the bar would have solved the problem (Of course then you wouldn't have had the speedboat scene at all but it's still pretty dumb).
Suggested correction: Characters doing stupid things doesn't constitute a stupidity entry. That was part of the joke, that Chet spent all the time telling his son to remember to let go of the rope if something goes wrong, but then forgets his own advice in the heat of the moment. People do stupid things in real life all the time.
Well how does this not count as a Stupidity then? You just said it was and there was no need for him to stay holding onto the rope.
Stupidity is basically a minor plot hole, something small that doesn't rise to the level of an plot hole entry. Characters are still allowed to do stupid things though if it's not a plot hole (otherwise everything Lloyd and Harry do in all the Dumb and Dumber movies would be stupidity entries).
Stupidity: When Steve Martin reaches the beach with the wheelchair, he tips it over, giving the illusion that he fell out of it. However, with where he starts crawling on the beach, it's tipped the wrong way. If it was that way, he would've been on the other side of it. A clever con-artist should know better.