Near the beginning of the movie when the native is watching Johnson trying to catch fish, what kind of gun does the native have? It looks like a side by side with a rifle barrel on the right side and a shot gun on left. Was a gun like this ever produce?

I don't believe Indians or white people had such guns back then.

I think it may have been what's called a cape gun.

"He says you fish poorly."

Muzzleloaders in this configuration are fairly common. Side by side and over-under. Usually one rifled barrel and one for shot.
Cape guns were English make for the South African market.

I think what you are seeing is a ramrod. I noticed it, too.

Called a Drilling. Very popular on European driven hunts, shooting boar and stag as well as pheasant and partridge. A rarity for sure but not impossible for a Native to get one through hook or crook. A Cape Gun is similar but only 2 barrels.

Nope, it isn’t a drilling. A drilling is a shotgun x shotgun with a rifle underneath. A cape Gun is a shotgun x rifle.

Drillings are 3 barreled guns by definition. Most of these are cartridge guns also. The OP was talking about a muzzleloader.
The only reasonable Indian gun for the time frame was the Northwest trade gun or as mentioned any gun acquired by trade or recovery.
The type gun shown in the movie is not correct for the time frame-most were late percussion, say 1850-1880.

in one scene he had a handful of traps with a v cutout in the pan. i wouldn't worry to much about time period accuracy of equipment.

I thought it had 3 barrels. Yes two is a Cape Gun. A Paradox has rifling at the end of the Barrel. These all are commonly called combination guns. Very handy on driven hunts but almost all antiques now days. I did miss out on Sauer drilling for $1500 recently. 16 gauge and 7x57. Would of been sweet.

I read that cape guns were sometimes gifted to native American leaders.

That's only because they couldn't find any dukes.....................

North west trade gun was the typical Indian firearm. some fancier "chiefs grade" smoothbores were also
Gifted by England during the war of 1812. Hudsons bay traded some double side by sides later into the early 1900s. I have seen a lot of the Indian guns in museums all over the country and have yet to see a cape gun.

Mybe korea wasn't invented yet?

Maybe the prop guy just though the gun would look cool in the shot.

Some but limited info here :

http://www.imfdb.org/wiki/Jeremiah_Johnson

Most likely reason. In the John Wayne version of the Alamo, there is a Nock volley rifle used,and there is NO documentation of it's existence in the whole of Texas. the movie prop people thought it was a neat addition, even if historically ridiculous.

like when the kid smelled the beaver lure and almost puked,hahaha. Any good beaver lure use I enjoy the smell of.nice castor or birch or poplar oil smell.

I've noticed that before.