I looked on Wikipedia to see images of Harriet Tubman who was severe looking with possibly only a hint of a smile in one picture, so the actress chosen for this part was a good look alike.
Cynthia Erivo acted lively and cheerful in the parts when she was younger, before she fled. I don't believe she could've run off in the middle of the day totally unprepared. A bit intense in her acting if a bit haughty. Many parts were unrealistic. The movie portrayed the escapes as something easy to do other than the distances needed to be covered. At times I wondered if I was watching a hallmark movie, slightly sappy. The slave owners were depicted well, especially their treating their slaves like loved pets, but ones that could be sold or kicked around if they were in a bad mood. When president Obama was still the U.S. president in early 2016 the treasury secretary, Jack Lew put plans in motion to put Harriet Tubman's image on one side of the U.S. $20 dollar bill and have the original picture of Andrew Jackson (a slave owner) put on the other side, but in 2017 when Trump became president. The new treasury secretary, Stevin Munchin squashed the plan. Such a shame as the United States is supposed to be the land of 'The Strong and the Free'. I hope the U.S. plan for her picture to be on the 20 dollar bill is revisited in the future as it would show that equality and freedom are different from the ancient days. Who knows, maybe one of our Candian bills could repesent this aspect of freedom?