The film is set in Victorian London, yet no musicians or their musical instruments are ever seen at the music hall - not when music is being played to accompany Dan Leno & his troupe, nor back-stage with the other performers and the stage crew.
The film is set in the early 1880s with flashbacks; yet, Lizzie is seen wearing "lamb chop" sleeve-style dresses/bodices/coats - brought into fashion in the 1890s. Sleeves would have been close fitting to the shoulders in the 1870s-1880s.
Dan Leno refers to Lizzie's attraction to the stage using the term "the roar of the greasepaint". The original cliché is "the SMELL of the greasepaint, the roar of the crowd". The odds of anyone switching "crowd" with "greasepaint" prior to the creation of the 1964 Leslie Bricusse/Anthony Newley musical "The Roar of the Greasepaint, the Smell of the Crowd" would be minuscule, since as quoted it makes no sense at all.
In a few close-ups you can see Olivia Cooke's character 'Lizzie' has modern 'invisible' teeth braces at the bottom of her teeth.
When Eddie Marsan's character 'Uncle' strips off to reveal a chest full of tattoos many are obviously 'temporary' stick on ones (especially below his right shoulder).
The great Dan Leno first appeared on stage in 1884 - so he became popular in the late 1880s and 1890s. Karl Marx died in 1883, one year before Dan Leno first took to the stage. There could be no point in time when someone could meet both Karl Marx and a successful, popular Dan Leno.
At one point, Dan Leno makes reference to "the roar of the greasepaint". Surely the well known musical with that phrase was a twist on the original which must have been "The smell of the greasepaint, the roar of the crowd".
The story is set in Limehouse, which falls under the Metropolitan Police 'H' Division. However, Constable Flood wears collar numbers with the prefix 'P' which is Camberwell, some miles from Limehouse on the opposite side of the Thames.
Early on Lizzie Cree says, "It betrays the suffering of women. My gender become inured to injustice". The character should have said, "My sex becomes inured...". Substituting "gender", a grammatical term, for "sex", meaning male or female, is a modern genteelism.