These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Big Lipped Alligator Moment: The particularly odd scene where the Ghostly Trio goes inside Dr. Harvey and changes him into Clint Eastwood, Rodney Dangerfield, Mel Gibson, and the Crypt Keeper. It is never mentioned again throughout the rest of the film, nor do the trio ever use their apparent morphing-abilities again.
In the first film, when the Ghostly Trio eat. The food they shove into their mouths are just as animated as they are.
Moral Event Horizon: In A Spirited Beginning, Brock locking Chris in the mansion and his complete Lack of Empathy when he's told that the bomb planted inside the mansion could have killed Chris. Really, he and one of his lackeys (the other having made a Heel-Face Turn) deserved far more than having them hung on a tree by their underwear.
Also, in A Spirited Beginning, when Chris introduces his Dad to Casper, but he doesn't show up (Having been kidnapped by his uncles), Chris's Dad demonstrates in one scene, that he is one of the biggest douchebags of a Dad for any character in a kids' movie of the 90's. It can also give the idea that this scene traumatized several kids due to how douchy Chris's dad acted in this scene.
In the first film, when the Ghostly Trio nearly cross this when they briefly consider murdering Dr Harvey in order to make him a ghost for them to hang out with. They don't go through with it, but they were seconds away from carrying it out.
Nightmare Fuel: The Ghostly Trio's first impression can be terrifying. Double for the way they scared Dr. Harvey.
Tear Jerker: Casper telling Kat the story of how he died. Ghosts gradually lose their memories of their lives, so it's particularly sad that Casper - who may have been dead for quite a long time - can still recall his final day as a human so vividly.
James and his quest to reunite with his lost wife's spirit. He does his best to be a good father for Kat's sake, but Amelia's death left him so broken that he's been dragging his daughter all over the country just for the chance to see his wife again.