How this movie should have ended
Pretty much everyone agrees that the ending to Nightmare City is one of the worst possible choices the writers could have made. It worked 30 years earlier when it was relatively new for Invaders For Mars, but it doesn't work if you've already seen that movie.
So, how should this movie have ended? My answer is fairly simply. Take out everything from when Dean wakes up and after. End the movie at the end of the theme park section. It would make a wonderfully nihilistic ending in true "zombie" movie fashion.