Trivia: There is a theme of upside down being bad. The girl in the train stands on her head before the crash. The son is watching TV upside down. When Mr Glass falls down he falls on his back and sees the figure he is chasing upside down. When Bruce Willis breaks into the train wreck, the warning sign in the gates are upside down. Willis falls head first into the pool. The comic book given to Elijah is first viewed... you guessed it upside down! Not a mistake, but great directing.
Trivia: Samuel L Jackson has large hair to give a hint at the ending. Remember he says "Villains tend to have heads that are in disproportion to their bodies."
Trivia: The end credits list Robin Wright Penn's full maiden name as "Audrey Inverso". In keeping with the theme of the movie, the name sounds like a comic book character's name. The name Inverso also is consistent with all the reflective and upside down shots in the movie. Finally, the name is reminiscent of the "two sides of the spectrum" that Bruce Willis and Samuel L. Jackson inhabit.