Other mistake: Towards the end of the movie, when the mobs are breaking into stores/houses, the police come to try and stop them. The mob starts to throw rocks at the police. You can see one of these rocks, which look like they should be heavy, bounce right off of one of the officers' heads, and just bounce around as it hits the ground, like it weighs nothing at all.
Other mistake: In the sequence where the "Natives" celebrate the 16th Anniversary of their victory over the "Dead Rabbits," we can see that the year is 1863 while the battle shown in the beginning of the movie happens in 1846. Shouldn't they have been celebrating 17th anniversary instead of a 16th?
Other mistake: In the scene where Jenny is showing Amsterdam the advertisement for the ship (the Commodore) leaving for San Francisco, the movie makers made a misprint on the card. On the sail of the ship it says "Randolph M. Cooley - 118 Wall St". In the low right corner of the card, the address is "Randolph M. Cooley - 118 Water St. - Cor. Wall" (corner of Wall St.).