Factual error: The film is set in 1884. The locomotive used in the scene on the platform is engine no. 2857, a GWR 2-8-0 that was built in 1903, 19 years after the film is set. (00:04:35)
Continuity mistake: Enola's mother draws the final line through a set of four lines, which are not visible when Mycroft looks at the wall. (00:07:38)
Plot hole: No sooner than the film begins, Mycroft becomes the legal guardian of Enola; Sherlock accepts it without question. How on Earth did that happen? No coroner would grant a transference of guardianship just because someone's mother stepped out of the house and didn't return for a day or two. (00:11:37)
Suggested correction: The brothers obviously think that Enola's mother is out of her mind; Being the elder brother, Mycroft would immediately have had to take responsibility over Enola. Even if the mother did only go away for a day or two, Enola would still have required a guardian.
The brothers might as well think whatever they want. The UK's laws still mandate an inquest and a coroner's decision.
Factual error: Mrs. Harrison travels to a random, remote country mansion (kilometers away from any civilization), meets a woman who is not her pupil, forcibly takes her measurements, insults her, and slaps her! Nobody in the right mind would do that because they know they would be murdered, harmed, or handed over to the police for trespassing, assault, and battery. (Such outcomes are recurrently portrayed in Sherlock Holmes stories.) Schoolmistresses did use corporal punishment but only on their pupils and within the bounds of school, where they have relative safety. To make matter worse, Mycroft warns Mrs. Harrison in advance. He describes Enola as "unbroken", "a wild and dangerous woman", "a wild child." (Indeed she is; she beats people during the rest of the film. How did Mrs. Harrison escape unscathed?). (00:11:43 - 00:13:46)
Suggested correction: How was she trespassing or going to a 'random' mansion? Mycroft, who owns the mansion and is Enola's guardian, specifically invited her there and enrolled Enola as Mrs. Harrison's pupil. Slapping Enola was out of line (Mrs. Harrison seems to immediately regret it), but not unheard of. And Enola still holds out hope that Mycroft will change his mind. Fighting Mrs. Harrison would just prove to him that she needs discipline. She'd rather play it safe and escape before being sent to school.
The slap wasn't just out of line; in the real-world 19th-century England, it was defensible by death. Enola could kill all three, call the police, and allege killing trespassers. The worst verdict an inquest could return was "death due to misadventure." Or Enola could just kill all three and nobody would be the wiser. Read the original Sherlock Holmes books to find out why. Things didn't happen as they they'd happen in real-life... because the director said so.
Except it would be incredibly easy to prove that they'd been there at Mycroft's (the homeowner's) invitation, and Sherlock and the housekeeper also knew they were guests. It would also seem rather out of character for Enola to kill a teacher, let alone a couple of innocent dressmakers, don't you think?
Proof of Mycroft's invitation merely changes the inquest's verdict from "lawful killing" to "death by misadventure." It is out of character for a real-world Ms. Harrison, the epitome of decorum, to slap someone outside the school without fear of reprisal. (Does she have no self-preservation instinct?) It is out of character for a real-world Mycroft, an upper-class mansion owner, not to kill Ms. Harrison in defense of his honor. The Mycroft of this film is a 21st-century American redneck.
He's a redneck because his first response wasn't to kill a woman? It's a moot point. Enola never told anyone she'd been slapped.
Mycroft Holmes, the smartest man in the world, must have deduced something was wrong at point 13:53 when he saw the distressed Enola. After all, his inferior brother Sherlock has made more impressive deductions. And yes, the Englanders of that era could be deadly when somebody stepped out of bounds. Most importantly, you've stopped defending the original mistake and are now content to attack me for whatever reason. I think we're done here.
Continuity mistake: The school uniforms completely change halfway through the school portion of this movie. It's the whole top white piece of the dress. (01:19:46 - 01:22:29)
Plot hole: Enola and Tewkesbury make an unpremeditated decision to visit the Basilwether estate. This decision was made on the spur of the moment, and no-one knew about it. but when they arrive, Linthorn, who is supposed to be in London looking for Tewkesbury, is waiting in ambush to kill them. (01:32:45 - 01:34:31)
Suggested correction: Linthorn saw them in London. He travelled back to the Basilweather estate, and waited for them to slowly make their way there.
Enola and the young Tewkesbury were in London two weeks prior to Enola's forced enrollment in a boarding school where she was supposed to spend her next few years! Furthermore, there is no evidence of Linthorn having seen them.
Continuity mistake: When Enola and Tewkesbury approach Basilwether, its lights are on. When they enter, its lights are off. (01:34:30 - 01:35:30)
Factual error: Linthorn meets his end when Enola knocks him off his feet. He hits his temple against a heavy and sharp furniture protrusion. Death must have been instantaneous, but instead, he lives to speak a few words. (01:39:18 - 01:39:55)
Suggested correction: He suffered a serious injury, but didn't die right away. There's no indication death was instantaneous.
Every word of what you said is correct. And that's the mistake! Death must have been instantaneous... that is if there was any. A "head trauma", as medical doctors call it, does not have slow-timed effect. The effects range from dizziness to more severe ones, e.g. loss of consciousness, loss of memory, or death. All of them are instantaneous.
Factual error: At the end of the movie Enola rides a bike on the right side of the street. The shot widens and two horse-drawn buses come into view, also on the right side of the road. The movie is set in exactly 1884 (votation). It became mandatory to drive on the left side of roads in England in 1835 (Highway Act). (01:56:33)
Factual error: When Tewkesbury sees Enola's rented room, she asks if he was expecting a room at the Ritz. The Hotel Ritz in London opened in 1906, and the Paris branch opened in 1898. This film is set in 1884.
Factual error: The old percussion double barrel shotgun is firing modern shotgun shells, which would never work or fit in that gun, and furthermore are also made of plastic, wrong for the era.
Continuity mistake: At the end of the film when Enola is deciphering the personals advert she initially writes "Meet me a" but when it goes back to her writing afterwards it has changed to "meet me royal..."
Factual error: Viscount Tewkesbury uses Marquess of Basilwether as a secondary title. However, marquess is two ranks above viscount in British nobility; a secondary title would only be of a lower rank, and the only rank lower than viscount is baron.
Continuity mistake: When Sherlock says "those kind of mysteries are always the most satisfying to unpick", he's smirking in the closeup, but in the next wider shot from the side he's looking deadly serious.
