Freddie states she is a private detective because women could not be police officers. Indeed, although since 1887 the Toronto Constabulary hired police matrons (women who have charge of the women and children detained at the stations or jails), the first female police officers were not appointed and attached to force until 1913 (a decade after this episode takes place), when Mary M. Minty and Maria J. Levi accepted their positions. Women would not be placed on regular patrol duties with men and expected to do the same work, however, until 1974.
In this episode Crabtree invents a device called lapboard which is a small chalk board one can unfold and put on their lap in their travels to take notes, similar to today's laptops.
This episode takes place in 1903.