How could DJ and Nebbercracker have possibly returned all the stolen toys to their rightful owners after the house was destroyed? DJ's hobby was spying on Nebbercracker, and he made logs whenever the man took what landed on his lawn.
DJ felt guilty for what happened to Nebbercracker and believes he's murdered him. Keep in mind that he's only 12 years old. Imagine the grave psychological implications a kid his age would've suffered if Nebbercracker hadn't returned near the end of the movie.
If the deeply unsettling nightmare involving a large, shadow hand attacking him in his sleep is any indication, DJ was already starting to suffer from the trauma.
If Nebbercracker constantly warned children they'd be eaten alive and later revealed to DJ that his house attacks anyone who comes near it, that probably means that the Monster House has most likely devoured other human victims in the past, and Nebbercracker has witnessed it.
This is later confirmed in a graphic novel based on the movie, which has Bones explore the house's grotesque basement, and he comes across skeletons of a mailman, a milk man, a salesman, a dog with a frisbee still in its mouth, and many others. Keep in mind how long those people must've been in there, crying for help, and having nobody hear them until they all ultimately starved to death.
This raises even more disturbing implications. Nebbercracker carries a terrible burden of living in a man-eating house. All this time Nebbercracker was hiding thousands of dead bodies in his basement, and since he is seen by the entire neighborhood as a weird, crazy old man who ate his wife and talks to his house, he is probably unable to tell anyone because no one would believe his house was responsible, and would most likely be deemed as a murderous person.
It becomes more disturbing the more you think about it. If the house hadn't uprooted itself from its foundation to chase Nebbercracker and the kids through the neighborhood, then all the victims we saw in the movie (Bones, the policemen and the dog), would've suffered the same fate.
Horrifically, Constance dies from the one thing everyone was bullying her over: her weight. She only falls into the cement pit because her feet are squeezed into shoes she's too fat for and she can't regain her balance. The kids, in this situation, were right - though went about it wrong - because if she was thinner, she could have regained her balance or not fallen at all.
If the original script for the movie is relevant to the final product, then that would mean Mr. Nebbercracker never leaves his house in fear that it will attack innocent people in his absence. How has Nebbercracker been able to survive for so long inside that home?
A graphic novel based on the film also suggests that Nebbercracker has tried to leave, but the house won't let him.
A line from Mr N. in the original script makes Nebbercracker's captivity in the house all the more tragic.
He even mentions to DJ at the end of the movie, that he and his wife had been trapped for 45 years.
Alternatively they were instantly grinded up by the house's throat.
The kids who threw eggs at Constance and made her fall to her death are going to live the rest of their lives with the knowledge that they unwillingly murdered someone.
Let's just say that if you're going to throw dynamite into a fireplace, you needn't worry about lighting the fuse first.
First, you could counter-argue that with the supernatural being involved, it's better to be safe than sorry. But even if you agree that it was a dumb move, perhaps DJ as a kid might not have known better. More importantly, at that time he was busy surviving against the house so in the heat of action such a mistake is more understandable.
Actually, an exchange between DJ and Chowder in one of the movie script's early draftsacknowledges this. It was merely cut from the movie.