Stupidity: When Dr. James Harvey dies, there should be a body left behind in the manhole. After Kat and Casper revive him in his ghost form in the Lazarus, he comes out with a body (and clothing). One can assume that there are now two bodies of him, one alive and one dead. That would make an interesting article in the newspapers of the next day.
Stupidity: A movie always needs extra conflict, but Julie's reasoning for walking out on Marcus and Mike is one of the dumbest. "If his wife can find us, I'm a LOT better off on my own." What sort of logic is that? She's the wife of his best friend. Of course she knows where he lives. (01:32:45)