Moving from CBS for its first two years of production (Due South (1994)) to first-run syndication, the new production company wanted to have the premise inserted into the opening titles so that first-time viewers wouldn't be confused as to what a Canadian Mountie was doing in Chicago. Not wanting to alter the opening titles, Paul Gross opted to simply state the premise in each episode with the line, "I first came to Chicago on the trail of the killers of my father, and for reasons that don't need exploring at this juncture I've remained, attached as liaison with the Canadian Consulate." This became a running gag throughout the third season, as the writers found various ways to insert the line in different ways into almost each script, whether it was spoken by Fraser or other supporting characters.
While Constable Fraser has sustained various injuries during the run of the series, they have only happened when he chose not to wear his hat, or it had been knocked off his head through various circumstances. This has earned his hat the nickname, "The Stetson of Invulnerability."
In the episode "Mountie Sings the Blues" from the first season, officers Huey and Dewey try to write a country and western song. The lyrics that they are working with ("Don't call me for supper, if you don't mean to feed me. Don't tell me you love me with that gun in your hand.") are from the title track of Paul Gross and David Keeley's first CD, named "Two Houses".
Leslie Nielsen's recurring character - legendary mountie Buck Frobisher - was named for 16th century explorer Sir Martin Frobisher, who explorer the northern areas of what is now Canada searching for the Northwest Passage.
Fraser is named after the Fraser River in British Columbia, Canada. Diefenbaker is named after John Diefenbaker, Prime Minister of Canada, 1957-63. Thatcher is named after Margaret Thatcher, Prime Minister of the UK, 1979-90.
For a time, this was considered the most popular Canadian-based and produced TV series ever shown on a US network. After a break in production following the first two seasons, the producers were able to obtain international funding to continue production.
The series finale, "Call of the Wild", involved a scene in which 20 Mounties parachuted from a Hercules aircraft. Two parachutists momentarily became entangled in midair but managed to untangle themselves and landed safely. This segment was shot over the Spray Lakes in Kananaskis (Alberta). The Canadian Forces Skyhawks from CFB Trenton (Ontario) were hired to perform the stunts.
Ray's car throughout the 1st two seasons (apart from the Pilot) is a green 1971 Buick Riviera. It has also mistakenly been referred to as a 1972 Riviera (as some of the backup vehicles were that model) in a couple of episodes.
David Marciano opted not to return to the series after a contract dispute with Alliance Atlantis, the production company. His character of Ray was replaced by Callum Keith Rennie. The writers wrote Rennie into the story by saying the original Ray Vecchio had gone deep undercover with the mob which was why the appearance change of Ray took place.
The first season episode "Victoria's Secret" was originally the season finale for that season and the series finale but when it was announced the series would be renewed, "Letting Go" was created to answer the questions of what happened after VS.
The character of print journalist MacKenzie King, who appeared in two episodes (played by two different actresses) was named for former Canadian prime minister, William Lyon MacKenzie King, who served in the 1920s.
Catherine Bruhier moved to Los Angeles after Due South (1994) was cancelled and was pursuing a career there. She only appears in three Due South (1994) episodes until her character, Elaine, graduates from the police academy.