At the end, I wondered in what year the action had taken place. In the novels, Enola was born in 1874. She was therefore sixteen in 1890. But, in the film, we see the date 1884 associated with a drawing illustrating her birth.
In this case, she was sixteen in 1900.
Further on, we discover an illustration, inspired by Paget's, when she presents her brother Sherlock.
We recognize the image of the Solitary Cyclist, the original of which was not published until January ... 1904.
This does not make all the characters younger, especially Madame Holmes.
But, see what is here:
1884! And we can even specify June 17 after checking the calendar for 1884.
Thus, Enola would have been born in 1868.
But here's something that changes everything:
Technical Advisor for Legendary Pictures's "Enola Holmes," the noted Sherlockian Leslie S Klinger states: "Many have misread the context of the date at the beginning. The film clearly TAKES PLACE in 1884, when Sherlock is 30 and Enola is 16. The Reform Bill--a very real and important piece of legislation--was enacted in 1884 and of course it is critical to the plot. There is nothing in the script that contradicts the Canonical evidence. Holmes in fact DOES mention his sister, in "The Copper Beeches," but we learn nothing of her. While it's unlikely that Mycroft gained in stature between 1884 and 1889-90 (when we first see him in "The Greek Interpreter"), no one seems to have been bothered by Christopher Lee or Mark Gatiss playing Mycroft (in "The Private Life of SH" and the BBC's "Sherlock," respectively)."
Wait, wait, wait ... A sister in COPP?
This is what Sherlock Holmes says in COPP:
"I confess that it is not the situation which I should like to see a sister of mine apply for."
"And yet he would always wind up by muttering that no sister of his should ever have accepted such a situation."
My dear Klinger, it is a "mention". Oui, oui, oui... 😃