In series 1, the same house is used for Lydia Andrews' house in Cocaine Blues, the Waddingtons' house in Death at Victoria Dock, and Aunt Prudence's house in Murder in the Dark. After series 1, the house is only used for Aunt Prudence.
Although set in the 20s, at least two songs used for background mood, "My baby Just Cares for Me" and "Minnie the Moocher" were written in the 30s.
Although the producers have obviously gone to some trouble to use period firearms suited to the 1920s era, nevertheless Miss Fishers trademark revolver is a Chiefs Special model that was introduced in America on 1950. Similar American revolvers by Smith & Wesson from the 20s era were distinctly different on appearance.