This episode's title, Manifest Destiny, refers to America's doctrine, which states that the country has an inevitable destiny and right to expand the American border to the Pacific Ocean.
Jacob reads a newspaper article that refers to the "recently" deceased Jedediah Smith. This scene takes place in 1836. Well, the news during that time must be really slow because Jedediah Smith actually died in 1831, at the young age of 32. However, they were accurate in saying he was killed by Commanches while at a watering hole on the way to Santa Fe.
This episode was originally titled "Migration" before changing to "Manifest Destiny" for its initial airing.