Artistic License History / The Spanish Princess

• Though the show avoids past clichés in casting pale skinned, red-headed Charlotte Hope, as the real Catherine of Aragon was said to be; the same courtesy is not extended to her mother Queen Isabella, who is played by Alicia Borrachero (yet Catherine was said to be the daughter that resembled her the most). This choice is funnier if you know that just a few years before, Borrachero had played the Moorish Queen Aixa opposite the blonde Michelle Jenner's Isabella in Isabel.
• Joanna of Castile is portrayed as an atheist who declares her disbelief in God to both her sister Catherine and her husband. However, though Joanna was reportedly impious and expressed religious skepticism, it never went this far. Reportedly, she really was tortured for saying skeptical things, and thus would presumably refrain (even or especially assuming this included atheism).
• Although Isabella of Castile was present for the sieges of Malaga and Granada and accepted their surrender in person (and of other cities and castles during the previous War of Castilian Succession), she never actually fought in battle. In this, the show makes her a Composite Character with her husband Ferdinand II of Aragon, who was the one who fought and is completely absent.
• Likewise, Catherine wasn't even at the Battle of Flodden, let alone riding her charger into the thick of the conflict and killing soldiers; when word came to her of the victory she was nearly 300 miles away in Buckingham. Again, no one was going to risk a heavily pregnant queen on the battlefield. While she did ride north from London to provide inspiration and moral support to the troops, it's debateable as to whether she was wearing armour or not; several sources record she was bringing 1500 suits of armour to help the English forces, rather than wearing it. Flodden was a stroke of military and political genius by Catherine as it was; she doesn't have to put on armour to make that true.
• Catalina de Cardones and Catalina de Motril were not the same person. The first was a Spanish lady-in-waiting of the Cárdenas noble family; the second, a Moorish slave. However this confusion is not original to the show or Gregory, but goes back to the 19th century. Since both went to England in the service of Catherine, we can rule this as another Composite Character, voluntary or not.
• While several of his fellow humanists worked as tutors to aristocratic children during their careers, Thomas More never did.
• Henry is revealed to have been trading spicy letters with Catherine while she was still in Spain, under the pretension of being his brother Arthur. This is complete fiction, nonetheless because Henry was only 9-years-old at the time.
• Henry is shown to be extremely disappointed when Mary is born, to the point that his wife's failure to produce a healthy son is practically all he ever talks about. Contrast with the real Henry, who was glad at least one of his children survived past infancy and it wasn't until Catherine hit menopause that he grew desperate for an heir. Catherine herself isn't much better, since in real life she loved her daughter very much, was very involved in her bringing up and education, and likewise hoped that other healthy children, sons in particular, would follow; one of the reasons she was so adamant in refusing an annulment was because it would have stripped Mary of her right to the throne and made her a bastard.
• Catherine's awful treatment of Bessie Blount would most definitely not be allowed by the real Henry (minus the incident with Anne Hastings, which happened early in Henry and Catherine's marriage, Catherine was rather known to look the other way when it came to Henry's infidelities). Henry rather removed Bessie from court soon after learning she was pregnant - mostly in order for the birth of his illegitimate child to be as discreet as possible. It wasn't until the child turned out to be a (mostly) healthy boy that Henry's joy overrode his fear of scandal. Even then, when Henry Fitzroy was presented to court as Duke of Richmond, not only Catherine was present, but she was said to be mostly placid during the entire ceremony, since, well, queens had to grin and bear it back in those days...
• It is mentioned in passing during the Field Of The Cloth Of Gold episode that Louis XII was the father of Francis I. Which is both nonsensical and funny, since the showrunners avoided an interesting parallel between Louis and Henry. Louis XII was so desperate for a son he married only a few months before his death, when his health had already started to fail (people then joked that he died because of being too enthusiastic with his young bride). He had two wives before Mary Tudor - Joan of Valois, who was said to be infertile on the account of being a hunchback (when the truth was that Louis barely slept with Joan and neglected her for years), and Anne of Brittany, whom he married for her riches, but who had trouble producing a healthy child. Out of five children she had with Louis (she had already born six to her previous husband, none of which survived) only two girls survived their parents. Because French customs forbade passing of the crown through a female line, the throne went to Francis, who was a distant cousin of Louis XII and who then married his older daughter Claude to seal the deal and gain the fortune she inherited from her mother.
• Francis I also questions the legitimacy of Henry's daughter Mary, which in reality he wouldn't have done, especially not in public; the marriage of Henry and Catherine of Aragon was considered valid because of a papal dispensation. To make matters worse, the reason why he questions it was because of his firm belief at the time that the Pope doesn't have the power to make an otherwise illegitimate marriage permissible. Francis, at least in public, was a good Catholic and would never question a decision of the Pope without a very good (political) reason. In the show, his only motivation to do so is to ask for a bigger dowry for Mary when discussing her potential marriage to his son - which is ridiculously petty. ^note  There were concerns on the Continent regarding Mary's legitimacy even with the dispensation, and this caused some difficulty while trying to find her a husband, but that's different from suggesting to the English monarchs' actual faces in public that their daughter is a bastard.
• In real life, Meg and her second husband Angus had a daughter named Margaret Douglas, who is Adapted Out here. Since Margaret Douglas was the mother of Lord Darnley, husband of Mary, Queen of Scots and father of James I, this leads to an Adaptation-Induced Plot Hole for the British royal family's future existence.
• While some people in the Protestant Reformation did deny the divine right of kings, Martin Luther did not go that far. Many Protestants supported book burnings, torture and capital punishment as well, and were hardly progressives as we understand the term today. There were also tolerant Catholics during the early 16th century such as Margaret of Austria, Erasmus, Michel de Montaigne and Margaret of Valois-Angoulême. While Thomas More did oversee the burning of Protestants, he wasn't the extremist the show portrays him to be and was actually in favor of some reform (as were other faithful Catholics at the time, in fact, including certain members of the School of Salamanca, all of which later led to the Council of Trent) and the translation of the Bible into English, albeit with a heavy oversight over the project.
• Cardinal Wolsey and Catherine of Aragon also have an exaggerated role in the Catholic reaction. In real life, they were not as involved in it as shown in The Spanish Princess. Similarly, Anne Boleyn's role in the Protestant Reformation is downplayed, and John Fisher and Bishop Gardiner are not shown either, ignoring the role they played in the Catholic reaction.
• The final episode has Maggie Pole taking revenge on Catherine of Aragon because she treated her badly at the beginning of the episode. It is unlikely that King Henry VIII would have taken Catherine of Aragon out alone to hunt, hurt her legs and left her there without her guards in real life. Her friction with Thomas More is likely played out for drama, as the two were both supporters of the queen in real life. They also have Catherine of Aragon giving serious consideration to shooting King Henry VIII and Anne Boleyn with a crossbow when she sees them together, which almost certainly never happened. The rivalry between Catherine of Aragon and Anne Boleyn is downplayed as well. The historical Margaret Pole was a loyal and loving friend of Catherine of Aragon and Princess Mary Tudor's beloved governess; not only is it unlikely she would betray both of them simply to stay in King Henry VIII's good graces, she even later died a gruesome death for her fidelity to Catherine and the Catholic Church.
• The scene where Henry and Catherine's infant son suddenly dies at her feet in the chapel is somewhat based in truth. Henry and Catherine did have a son who tragically died - however, in the show, he's implied to be at least several months old already (or at least old enough to be teething). In real life, he only lived for about seven weeks. In addition, it is extremely unlikely that Catherine ever nursed him herself, and neither Catherine nor Henry were present when he died (as per long standing royal tradition, he was almost entirely left in the care of others, including being fed by wet-nurses). The exact cause of his death has been also been lost to history.