In the shootout at the end, the rifle is clearly a small bore .22 caliber single-shot bolt action. However, the sound effects with each shot sounds as though it is a large caliber gun, with a loud boom and crack.
During the fight scene, a barrel is knocked over and the wooden barrel staves immediately spread open like a flower. It appeared to have the metal bands around it which should have held it together, but when it falls open it's clear that the bands were just painted on to allow it to open that way with dramatic effect. In addition, something must have held the bottoms of the staves all together to allow the top to open up like a flower while the bottoms seemed hinged.