The son threatening to shoot his dad...
Remember that intense scene where the son threatens to shoot David?
So apparently, the scene was inspired by the real-life story of George Reeves, the actor who played Superman in the 1950's. A kid wanted to test Reeves' "invulnerability" with a real gun, but he used a bluff to keep him from doing it by saying the bullet might bounce off him and hit someone else.
I don't know how it went down in real life or how Reeves reacted when he saw the gun, but it must have been scary as hell.