Indiana Jones and the Raiders of the Lost Ark features Harrison Ford's most famous scene, which was a complete accident.

When a man quietly reveals a gun to try and take a shot ... job of foreshadowing by establishing Indiana Jones’ most powerful fear in an early scene, and it speaks a great deal to his character ...

Or take "The Mummy," where, again, essentially the only thing we learn about the protagonist in his first scene is that he's good at shooting guns. So, what exactly is the intro to "Indiana Jones ...