You do know the backstory on that scene, right? As written, it was supposed to be a much longer fight sequence. Harrison Ford was sick on the day of shooting for the scene... something like explosive diarrhea and dehydration, ane he realoy wasn’t up for the whole elaborate sequence... so they changed the scene to what everyone saw in the final cut.
At least that’s what I’ve been told.
That's close to what I read .... similar about him being sick and all. The twist I read was that him pulling the gun was originally an ad-lib. Harrison Ford was past exasperated, and he just pulled out the gun and made as if to shoot the sword fighter. The director (I guess) decided it was better than making Ford do it over yet again the way it was scripted, and it was just so over-the-top comical (it's almost like a RoadRunner cartoon in a way), so they used the twist with the gun for keeps.
Note that in the final film his gun emits smoke, and the sword fighter immediately jumps and drops -- instead of giving Ford a "WTF?" or "Huh?" look. I'm pretty sure the original ad-lib wasn't used in the final, but rather they re-shot it so that it looked right with the effects.
In any case, one of the absolute best moments in modern films.