Factual error: In this episode we see Blithe get shot in the neck and are told that he died in 1948. In reality he was shot in the shoulder and survived. He later served in Korea and was promoted to master sergeant as well as receiving the paratrooper of the year award. Blithe died in 1967 while on active duty in Germany.
Factual error: Aetius' troops don't look anything like 5th century Roman soldiers. They are carrying a large rectangular shield, a pilum (a spear which was used for throwing) and a sword (gladius) on their right. This was typical for the Roman army until about the 3rd century A.D. In Aetius' time, the soldiers would have had smaller oval shields, a hasta (a lance used for stabbing and for fending off cavalry attacks) and a sword (spatha) on their left. Also, there would be an enormous amount of "barbarian" mercenaries in the Roman army (Goths, Vandals, even Huns.), so it was hardly a Roman army anymore. And where's Aetius' cavalry?
Factual error: The American flag shown waving outside the White House is the current present-day flag with 50 stars. From 1896 to 1908, (the time period that this show is set in) the US flag only had 45 stars as Oklahoma, New Mexico, Nebraska, Alaska and Hawaii were not recognised as states in that time period. The flag did not have 50 stars until 1960. (00:04:30)
Factual error: "Underground" is set in 1857 Georgia, yet the padded baseball glove August Pullman gives to his son is of a type used during the early 20th century. Before 1883 when padded gloves were first manufactured, gloves were either not used by baseball players or railroad brakeman's gloves were used.