 When Christopher Walken (qv) works with guns in film, he checks  them himself before each scene for safety reasons and his own  personal ease. During the scene when Sean Penn (qv) sticks a gun  in Walkens face, Walken checked the gun before the scene started.  Before the director had the chance to say "Action", Penn ran off  camera and shouted, "Give me the other gun!" He immediately returned  to Walken and started the scene. This is the cut that made it into  the movie, and Walken was really terrified.