Stupidity: Howard has the opportunity to shoot Jack at the end, but doesn't for no discernable reason; he's already committed multiple felonies, and shooting Jack would help cover his tracks all the better. In fact, he could even have just taken the cash onto the subway and left Annie behind while staying in full disguise as a cop.
Suggested correction: Howard Payne's taunting dialogue in the subway station suggests that he wants Jack to live a long life, tormented by the fact Payne was able to beat him. He doesn't become intent on murdering Jack until the dye pack goes off, ruining the money. After that, he tries to shoot Jack but runs out of bullets, then decides to beat him to death with the detonator but fails.
Stupidity: When doctors saw Julie being lifted up and dragged by Freddy, why didn't they try to help her or at least call security?
