Unbreakable (2000)

Character mistake: In the final scene, one of the newspaper clippings on the killer's office wall reads something like, "Huge Mudslide in Mexico: All Killed Expect Newborn." The penultimate word should be "except." (01:35:55)

Elijah Price: Now that we know who you are, I know who I am. I'm not a mistake. In the comics, you know how you can tell who the arch-villain is going to be? He's the exact opposite of the hero. And sometimes they're friends, just like you and me. I should have known way back when. You know why, David? Because of the kids. They called me Mr. Glass.

Trivia: The first and last name of Bruce Willis' character, David Dunn, begins with the same sound, like other comic book heroes such as Peter Parker, Clark Kent, Matt Murdock, and Bruce Banner.

Question: Why are there so many things that are upside-down in this movie? What is the significance of it?