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.
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)