The narrator erroneously states "When Lincoln issued the Emancipation Proclamation in January, 1863...". Though it had been written in the Summer of 1862, Lincoln's advisers suggested that he hold off issuing it until the Union had a victory (otherwise, they advised, it would look like a desperate act by a losing side in the war). That victory came on September 17, 1862, at Antietam (though tactically a draw, it was a strategic victory as Lee was forced out of Maryland and back into Virginia). With that victory under his belt, Lincoln signed and issued the Emancipation Proclamation on September 22, 1862, to become effective January 1, 1863, IF the southern states did NOT return to the Union. They did NOT, and the Emancipation Proclamation took effect, as scheduled, on New Year's Day, 1863, some fourteen weeks AFTER it had been issued.
The map used early in the documentary, when discussing the world Tubman had been born into in 1822, includes West Virginia. It has West Virginia as a free state, yet West Virginia would not exist until 1863. In the years prior to the Civil War West Virginia was part of Virginia and was considered a slave holding area of a slave holding state.