When Kynaston says, "I blame you for my death," he looks up at Maria, but in the next shot his head is back down.
As often happens in period dramas, many historical personalities and events are combined or rearranged to fit the dramatic narrative.
During his first meeting with the King, Mr. Kynaston takes a bow and addresses the King as "Sir". While it's acceptable to use "Sir" after the initial introduction, the first address should always be "Your Majesty".
"Sex" is used by characters as shorthand for sexual intercourse, a meaning the word didn't have until the 20th century.
The "naturalistic" acting, as Ned and Maria perform in the later part of the movie, wasn't done until the 19th century. The "series of poses" acting done in the early scenes was the norm for some time after the film is set.
The word "fan" (short for "fanatic"), meaning an enthusiastic admirer, was not used in this sense until the late 18th century.
The movie is set sometime between 1660 and 1662, but the style of dress the men are wearing wouldn't be worn until 1666. That is when Charles II introduced the 3 piece suit (coat, vest & britches) to the court. The fashion caught on rapidly. Within weeks all the men of court were wearing suits. Even Samuel Pepys began to wear a 3 piece suit with a few months. This was also the time when men began to wear something tied around their necks. This combination of coat, vest, britches and neck-wear has been worn by men in some variation ever since.
When Pepys is telling Kynaston to play a man's role, Kynaston's lips are out of sync with his speech in some shots.
Ned Kynaston, age 20-something, says that he's been playing women on stage for half his life, since he was a child. But at the royal banquet, the King says that the theatres have only recently reopened after an 18-year shutdown caused by the Puritan takeover.