In a nod to Sherlock Holmes, Miss Fisher's street address of "221B The Esplanade, St Kilda" can be clearly seen on an envelope addressed to Phryne Fisher at time index 16:32 into the episode.
When Dot (posing as "Martha Driscoll") is being interviewed by Miss Gaskin for a factory position, Dot pleads her need for a job by saying "My mother has the influenza," to which Miss Gaskin replies sympathetically "My aunt died of influenza," the same sentence that begins Eliza Doolittle's comical scenes at the tea party in "Pygmalion" and at Ascot in "My Fair Lady."
The calendar in Phryne's kitchen shows November with the first falling on a Monday. That would make the unspecified year, if in the 1920s, either 1920 itself or 1926. November the first would not fall on a Monday again until 1937.
Nowhere in this episode is it mentioned what exactly is being made at the factory, however, the building used for filming this episode was a sewage pumping station originally.
(In fact, at one point Jack mentions 'plumbing fittings', and at another it sounds like Phryne refers to the 'gasket factory', though it's more likely 'Gaskin factory').
(In fact, at one point Jack mentions 'plumbing fittings', and at another it sounds like Phryne refers to the 'gasket factory', though it's more likely 'Gaskin factory').