Both Saoirse Ronan and Margot Robbie rehearsed separately. Their scenes were filmed separately, Robbie's being completed the very day Ronan began hers. The first time that both actresses actually saw each other in character was during the pivotal scene where both met for the first time.

Saoirse Ronan was trained to ride for the first time by horsemaster Camilla Naprous who had earlier worked with Gal Gadot for her role as Wonder Woman (2017), using the very same horse named Prince.

Saoirse Ronan and Margot Robbie competed together in 2018 for many Best Actress awards, including the Academy Award, for their roles in Lady Bird (2017) and I, Tonya (2017), respectively.

This is the second time that Saoirse Ronan and Vanessa Redgrave were cast as the same characters on screen. Vanessa Redgrave played Mary Stuart in ''Mary Queen of Scots'' (1971). She also played the older Briony Tallis in ''Atonement'' (2007); Saoirse Ronan played the younger Briony.

The film is based on biography "Queen of Scots: The True Life of Mary Stuart."

In an interview with Entertainment Weekly, director Josie Rourke said that the meeting of the two Queens was also inspired by the 19th-century Friedrich Schiller play ''Maria Stuart'', in which Mary and Elizabeth talk face-to-face on stage. "The whole conception of the film for me was around that meeting.'' "We really wanted to have our version of that famous scene, with these two women looking at each other and being confronted with their choices - their personal choices, their political choices. It's a moment that's deeply personal."

At one point in 2006, Scarlett Johansson was attached to play the lead role, but dropped out, causing the project to live in development hell for several years.

The film is based on Dr. John Guy's biography "Queen of Scots: The True Life of Mary Stuart", and centers around the theory that the two may have met, and looked each other in the eye as they contemplated their kingdoms' fates. History buffs have objected to Guy's theory that the two met up. Guy told Deadline Hollywood that six years ago, "an auction house possessed documents that indicated the two complicit, yet warring cousins, had a meeting that was in the cards."

Margot Robbie is the second Australian actress to portray Queen Elizabeth I. The first was Cate Blanchett in "Elizabeth" (1998) and "Elizabeth: The Golden Age" (2007).

In August 2012, it was announced that Saoirse Ronan would play Mary Stuart. On 21 April 2017, Margot Robbie entered negotiations to play Queen Elizabeth I.

Margot Robbie was initially reluctant to accept the role of Queen Elizabeth, but after receiving a letter from director Josie Rourke about why she envisions her in the role, she accepted.

David Tennant appears in this film, which also features Elizabeth I. Previously, Tennant starred in the Doctor Who 50th Anniversary "The Day of the Doctor", which showed the Tenth Doctor having a romantic relationship with Queen Elizabeth I whom he married.

The crew on the film includes Academy Award winners costume designer Alexandra Byrne, hair and make-up designer Jenny Shircore and editor Chris Dickens; Emmy award-winning production designer James Merifield; and BAFTA award-winning director of photography John Mathieson.

Joe Alwyn who plays Queen Elizabeth's reputed lover Robert Dudley also is in the movie The Favourite about Queen Anne's attachment to Sarah Churchill and Abigail Masham. In The Favourite, he plays Abigail Masham's husband.

German-Romanian actress Maria-Victoria Dragus' English-language debut.

Susanne Bier was originally attached to direct, but dropped out due to scheduling.

On 15 November 2018, the film had its world premiere on closing night of AFI.

Saoirse Ronan and Eileen O'Higgins appeared in Brooklyn (2015) together.

In December 2016, it was announced that Josie Rourke would direct.

Joe Alwyn and Ismael Cruz Cordova previously appeared together in Billy Lynn's Long Halftime Walk (2016) as fellow soldiers.

Reunites Saoirse Ronan with Guy Pearce after Death Defying Acts (2007).