The sheriff auctions off the farm to Alameda Slim, saying "The farm, and all the livestock that goes with it, sold to Y. O'Del." A moment later, we see him auctioning off the chicks at the farm.
Alameda Slim's brand changes between a reflected version and the correct version between shots. For instance, when he is holding the brand towards the camera, the dollar sign should appear reflected.
After the cattle rustling, and Rico switches horses, the cattle drivers grab Buck's reins and break them. For the rest of the movie, they are whole.
Buck runs over the tracks of Slim and the cattle to confuse the cows. When the cows arrive, however, all the tracks are cattle hoofprints. (In the DVD audio commentary, the filmmakers explain that originally Slim, not Buck, was to scramble the trails; the backgrounds were from this original version.)
With the Willy brother sitting in front of Slim's map, Little Patch of Heaven doesn't show up, ever, until Slim moves the character out of the way. The outline of Little Patch of Heaven should show up, for instance, while the camera is pointing straight at the boy's face, however, it's not there.
The plan is to put 5,000 cattle on one train. Using the standard 36 foot, one deck, stock car common to the steam era, that would require a train about three miles long. The train they showed did not have enough cars (or engines).
In one scene a boy is blowing bubble gum. The film is set in the American old west. Bubble gum wasn't commercially sold until 1928.
The song Old McDonald wasn't written until 1917. The film is set in the 1880s or 1890s.