Before Javier Olivares joined, the project had little historical accuracy and gave more importance to romance. Gonzalo de Córdoba had an unhistorical sexual relationship with Isabel before her marriage, and the first season ended with her wedding to Fernando in 1469. Olivares pushed for more politics, gave more importance to the character of Isabel's mentor, Gonzalo Chacón, and set the finale in 1474, with Isabel's coronation.
For the third and final season, the network wanted to show plenty of Christopher Columbus arriving to America, but the budget didn't allow it. They tried to co-produce the season with a Latinamerican country, but the negotiations didn't arrive anywhere.
According to Javier Olivares, the dialogue in each episode of the first season has an average of 12 sentences lifted from documents of the time, such as letters written by the characters or contemporary chronicles like Alonso de Palencia's.
Fernando was the sixth legitimate child of Juan II of Aragon. His father was 54 years old when he was born.
At the time of his death, Enrique IV's closest blood relative after Juana and Isabel was no other but King Juan II of Aragon, who was first cousin of Enrique's father, Juan II of Castile. As a result, Isabel's marriage to Fernando gave her a powerful supporter and got rid of a potential threat at the same time.
First fiction show to be allowed to shoot in the Alhambra since Alice and Martin (1998).
The series was virtually canceled while it was put on hold before release, and Diagonal TV dismantled the sets to save money. Its massive success (averaging 20% share) led to its immediate renewal for two more seasons.
Before Isabel became Queen there were five independent monarchies in the Iberian Peninsula: Portugal, Castile, Granada, Navarre and Aragon. All but Portugal are part of Spain now.
Rodolfo Sancho, who plays Fernando, is 11 years older than Michelle Jenner, who plays Isabel. In real life, Isabel was 1 year older than Fernando.
Fernando was possibly the person or one of the people who inspired the character of The Prince of Machiavello. It's specially in The third season when we can see his ambition and his ideas.
The release was kept on hold for over a year due to the network's financial situation.
Verónica Echegui, Irene Escolar, Adriana Ugarte and María Valverde were all considered for the role of Isabel I.
It was believed for centuries that Enrique IV had a broken or deformed nose, but recent examination of their bodies revealed that it was his father Juan II who had a deformed nose, while Enrique's was normal. It is ignored if this was a genuine confusion of Alonso de Palencia (the first author to describe Enrique as deformed) or a deliberate smear campaign, since Palencia was a supporter of Isabel.
Years before playing Gonzalo Chacón in this series, Ramon Madaula starred as the titular character in Pedro I el Cruel (1989), which chronicled the conflict between King Peter I and his brother Henry - both of them great-great-grandfathers of Isabella I - that resulted in the rise to the throne of the House of Trastamara.
Irene Escolar's great-aunt Julia Gutiérrez Caba also played Juana de Castilla on an episode of Mujeres insólitas (1977).