Factual error: When reading out the list of the day's crimes, Artherton mentions two "teenaged" girls. Use of this term is not recorded in America until the 1920s and in Britain until the late 1940s. The series is set in 1889 and the speech used by the characters is consistently very much the speech of the time - it has not been updated for modern understanding.
Continuity mistake: Inspector Ressler is struck across the temple on his left side in the scene at the "bawdy house". He holds a hanky on that spot later and there are no visible marks to the right side (his right) of his face. Then, in the street scene afterwards and while looking at the Swedish Bakery he has marks on his right temple. Those marks are no longer there in later scenes such as Claxton's office.