Swedish actress Alicia Vikander had to learn Danish. Vikander spent two months in Copenhagen in Denmark learning Danish prior to principal photography.
As part of her audition process, director Nikolaj Arcel took actress Alicia Vikander out drinking to see how well she could understand Danish. Vikander faked that she could understand and speak it well but at the end of the process when Arcel told her she got the part she didn't understand what he was saying until he switched to English.
The film was shot in the Danish language but in reality, according to the movie's DVD interviews, the Danish court of the time actually spoke in French and German languages.
The film's director, Nikolaj Arcel, made a Director's Statement for the picture. It reads: "A ROYAL AFFAIR is based on one of the most dramatic events in Denmark and indeed European history; whenever I used to pitch the film to foreign investors, people had a hard time believing that the story was true, that these momentous events had actually happened in the late 1700's. In Denmark however, it is taught in school, more than 15 books have been written about it (both factual and fictional) and there has even been an opera and a ballet. I feel honored and extremely lucky to finally bring the full story to the screen. Tonally, I was inspired by the great epics from the 40's and 50's where films would often feel like literary works, structured around characters and the passage of time, and not clearly following the obvious screenplay roadmaps. But my creative team and I were also fired up by the idea of bringing the Scandinavian historical drama into the new century. We wanted to achieve this by adhering to a self-imposed rule; we didn't want to "show" history, didn't want to dwell pointlessly on the big official events, the fancy dresses and hairdos, or the way the food was served. Rather, we wanted people to simply experience the story through the eyes of the characters, taking the 1760's for granted. Even though the period is obviously there in the set designs, the costumes it was filmed and edited as we would have filmed and edited a film taking place in modern Copenhagen. Finally, Gabriel Yared and Cyrille Auforts' beautiful score has brought the film full circle, and home to its epic roots.".
The picture was Denmark's official submission for the Best Foreign Language Film of the Year category at the 85th Academy Awards held in 2013, where the movie won a nomination in this category, but in the end lost out to the Austrian film Amor (2012).