A choke pear (called "Pope's pear") is used to torture a convicted homosexual in the 2nd season. Choke pears were unknown before the 17th century, more than 100 years after the show's time frame. 15th century's punishments for pederasty were not so cruel (penalty, branding).
The characters in the series repeatedly make reference to distances in kilometers. The metric system was not invented until the late eighteenth century, three hundred years later.
In the first season, Giulia repeatedly threatens to send Pantisilea to Tierra del Fuego if she does not continue to spy on Lucrezia. The time frame is 1493-1494. Magellan is credited as the first European to visit Tierra del Fuego (and give the area its name) in 1500. The historical Pantisilea actually died before that date.
SPOILER:The recaps identify each episode as taking place during one month only, always following the month in the previous episode, but events in the episodes proper flow way faster than that. For example, the season 1 finale opens with Juan Borgia's death (June 1497) and ends with Perotto and Pantisilea's deaths (February 1498). The recap in the first episode of the second season, set 8 months after that, still claims to take place in 1493.