Mrs. Brackenreid mentions that before becoming a policeman, the Police Inspector had been a plumber is a clear reference to actor Thomas Craig, who plays him. Craig worked as a plumber for six years before becoming an actor.
The basic plot premise of the attempted kidnapping of a rich boy being bungled as the kidnappers take his considerably less affluent playmate was first used in Akira Kurosawa's "High and Low."
The footbridge over the railroad tracks where the ransom money was left on the railing is the same footbridge where Murdoch was thrown over the side in The Murdoch Identity (2010).
Adjusted for inflation, a ransom of $20,000 in 1897 would be equivalent to approximately $620,000 in 2020.
The character Bobby Brackenreid appears numerous times later in the series, but played by different actors: Jayden Greig from Season 6 to Season 9, and Aiden Bushey in Season 11.