When Ethan first finds the locket at Greenbriar, it is engraved with two sets of initials in a simple script font. When Ethan first gives the locket to Lena, the initials are the same, but the script is much more intricate and elegant.
Gatlin is a fictional town, but the Battle of Honey Hill was a real Civil War battle in South Carolina. The film gives the wrong date for it: December 21, 1864. It actually took place November 30, 1864.