Captain Parmalee splits up his Rangers into two group prior to the movement of the silver he says that 7 of them will be going to Soda Springs and meet him there and the other 6 will be staying in town. However, he is only addressing 12 men in the room.
After the Rangers are split into two groups, 7 end up staying behind in town (Gruber volunteered to stay behind with the original 6) leaving 6 plus Captain Parmalee to go to Soda Springs. However, when the camera pans the Rangers overlooking the mining area there, there are two groups of 3 and one of 2 (8 total Rangers)--there should have only been 7.
Jess Moran is urged to "Eat your steak -- you need the protein." Though proteins were known from roughly 1830, their exact role in human biology was not fully understood -- and Riley probably wouldn't have known the word "protein", anyhow. (Ditto for not allowing Moran to eat starchy foods -- but we won't go into that.)