Continuity mistake: During the photo shoot, after Tony takes the final shot and tells Margaret to "get dressed", so he can show her his place, she is wearing a different blouse and different earrings when she comes upstairs to his apartment.
Christmas Special 2017 - S2-E9
Continuity mistake: Price Albert's ice skates change after falling through the ice. Prior to the fall the ice skates have a curly blade front (appropriate for the time), upon emerging from beneath the ice the skates look like current models.
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.
Continuity mistake: During the Medici brothers vs. Marco Bello confrontation near the end of the episode Lorenzo grabs a candlestick to defend himself against Marco Bello's knife - you can even notice a candle slipping off the candlestick. As Marco Bello turns to leave the chamber, however, Lorenzo's hands are empty and the candlestick rests on the table. In the next shot he's holding it again, with the candle sitting atop of the candlestick. (00:47:30)
Factual error: At the picnic, a woman says she is going to New York by train. It is 1828. Railway passenger service in the United States did not begin until 1830 and it would not be possible to travel from North Carolina to New York until some years after that.
Factual error: Pierre Bezukhov's spectacles are of the type with nose pads, which were not invented until the late 1920's.