I watched it the other night too Hawg. And I found all the same problems you did, plus a few more. A lot of the rifles were 73 Winchesters.
When I first saw it advertised, I was excited. Then like you said, "Nevada, 1870" popped up on the screen, so I was really excited. I thought "Oh cool, it will be C&B guns. Then the very next scene he pulls out the nickel SAA's and I was instantly not interested anymore. Then after about the 5th mysterious change of guns, I nearly turned it off.