Spencer, the upcoming Princess Diana biopic starring Kristen Stewart, has just started filming in Germany but it's already receiving criticisms from royal experts because of its allegedly inaccurate plot.

As written by Peaky Blinders creator Steve Knight, the film's storyline revealed that it would take place within a three-day period during Christmas in 1991 in Sandringham, where Diana apparently decided she had to separate from Prince Charles. However, royal experts argued that Diana wasn't in Sandringham during that year.

Robert Jobson of The Royal Beat said that the Princess of Wales hasn't been going to Sandringham for the holidays since 1990. Majesty Magazine editor Ingrid Seward agreed with Jobson's statement and said that Spencer must be taken with a grain of salt as she speculated that the movie might simply play up the royal family Christmas holidays.

Production began this January, and the producers recently released the first photo of Stewart as Princess Diana. The reaction from royal fans has been surprisingly positive, with many commenting that the actress does look like the Princess of Wales. It was opposite to how the fans reacted when the film and Stewart's casting was revealed a few months back.

But one person reportedly unhappy about Spencer is Queen Elizabeth. According to Daily Express, Her Majesty could be upset at her cousin, Prince Donatus of Hesse, for allowing the production to use his mansion, Schloss Kronberg, to represent Sandringham in the movie.

Insiders claimed that the said property has been empty since the pandemic as Schloss Kronberg is actually a hotel. As with other businesses in the hospitality industry, Schloss Kronberg has had a huge downfall due to the lack of tourists.

However, another source said that Queen Elizabeth would understand her cousin's decision to permit the filming, despite its depressing storyline about the breakdown of Charles and Diana's marriage. The source described Prince Donatus as a nice and charming man on the Queen's good side.

However, it is understood that Spencer will move production to the U.K. in the coming months. But a big part of its filming will be in Germany as its investors are from the country.

Spencer will also star Sally Hawkins, Sean Harris, and Timothy Spall, but their roles have not been divulged. The film will also feature younger versions of Prince William and Prince Harry. The movie is expected to be out in theaters this fall.

In 2022, William and Harry will mark the 25th anniversary of Princess Diana's death. She would have turned 60 this year. Her sons will celebrate her birthday with the unveiling of her statue at Kensington Palace this July.