The burial marker was dated June 3, 1845 for Eliza Kent. Talk the next day was about the gold discovery in California. Some Mormon men working for mill operator James Marshall had been in a group landing on the west coast. The day reported for the discovery was January 24, 1848.
In the movie Joseph Smith is shown unarmed when he is shot and killed. In reality he was armed with a "Pepper" pistol.
Eliza Kent's tomb "wheel" shows she died in 1843 on the trek west. But Joseph Smith did not die until 1844 and the saints did not leave Nauvoo until 1846.