Sutter's wife Anna died 1881, one year after Sutter and it happened in Lititz, Pennsylvania. In the movie she died earlier in California, before Sutter himself.
Johann August Sutter immigrated to America in 1834, not in 1836, as in the movie.
The Californian Gold Rush began in 1848, three years before California was included into the United States as a new state. However in the movie the Gold Rush started after it was announced that California is a part of the USA now.
In a scene set in 1865 it is announced that it is the 10th anniversary since San Francisco was founded. San Francisco was founded on the 26th June 1776. And in 1856 the city became part of the USA. So in both ways it won't fit to the date.
Unlike in the movie Johann August Sutter actually received a passport in order to immigrate to America and a request to go to North America, also due to his business debts. In the movie he fled from an arrest.
As Suter and his two companions have to walk through the plains after their horses are stolen, a car crosses in the background. (At about 20:40)
The people are throwing a stick of dynamite onto Sutter's farm and burn it. The Hock farm was destroyed in 1865 but dynamite was invented in 1866.
James W. Marshall is killed in the movie in 1865. In real life he died in 1885.
Emil Sutter died in 1881, one year after his father Johann August Sutter. In the movie he is shown being killed at his claim along with his (fictional) brother Rudolf, long before his father.
Johann Sutter rejoined his family in 1841 on his Hock Farm. In the movie it happened in the late 1840s after the beginning of the Californian Gold Rush.