Stupidity: The whole movie happens for unbelievably convoluted causes. Despite their friendship and the simple fact that he still runs an occult shop (showing that he's not exactly insensitive to the past), Ray in years never spent a single moment to check on Egon's whereabouts, which he knew, or listen to him. The city has Shandor's name all over and any cursory investigation would have unveiled the connection. Assuming of course that Egon turned into such a lunatic he couldn't do the namedropping himself.
Stupidity: Spoiler: Everything goes well in the end and all the ghosts (and returning demigod Gozer) are sucked into a giant ghost trap. In fact everything goes so well that the trap selectively spares one specific ghost so it can have a lengthy farewell scene, hug and smooch every single character at leisure and leave on its own terms.
Suggested correction: The other ghosts were above the traps. The one specific ghost was not. Every time a ghost has been trapped they have been above the trap. In the first movie they even have to move slimmer to position him to be trapped.
This trap cluster was designed to cover an area, If Gozer could get away simply because he/she was standing one foot to the right or left of the nearest trap, the plan was flawed to begin with.
Even if Gozer stepped away from the traps, the Ghostbusters could simply wrangle her into the traps with their proton packs.
