In a scene set in 1461, Isabel expresses her frustration at the fact that the Queen piece in chess can only move one square at a time, like the King. This was really the case in Medieval chess: the changing in rules that made the Queen the most powerful piece in the game was first introduced in Valencia, Spain in the 1490s, possibly in homage to Queen Isabella herself.
The scene where a Jewish doctor (Sumaya Lubel) performs an artificial fertilization on Juana de Avis with a golden cannula is based on the chronicle of Hyeronimus Munzer, who visited Spain in 1495.
Javier Olivares wanted to begin with Álvaro de Luna's execution in 1453 and Gonzalo Chacón being declared tutor of the infantes Isabel and Fernando in Arévalo, which was in essence a ploy to take him away from the Court, but TVE vetoed any first scene that didn't feature Isabel.