While one of Cavendish's henchmen is fighting with the Sheriff, the henchman's hat is off, but in the next shot, just a second later, his hat is back on.
In the quotes section there are a number of quotes attributed to a John Reid. Nowhere in any of the credits is there a John Reid.
When Silver is first seen, he is laying down after being attacked by a buffalo. It is clearly visible he is shod - very unlikely for a wild horse.
A bison, even a bull, wouldn't attack a horse! They are herbivores and are even more skittish than cattle.
Obvious dummy for Collins as he falls to his death.
When Silver is laying down you see horseshoes. If Silver is a wild stallion why does he have shoes on all for feet.
Collins' scream as he falls to his death is clearly dubbed by a woman.
the sheriff is referred to several times as two gun and is credited as such. At no point is he seen with two guns.