After the better part of 3 seasons, Sully now chooses to ride bareback.
The bouquet of flowers on the table at Grace's Cafe at the end is the same bouquet Jake gave to Dorothy previously.
Belle didn't marry Sam Starr until she was 32 years old (when she was 14 her name was Maybelle Shirley).
In the late 1860's, when the story is set, Belle Starr was a mother in her early 20's, not a 14-year old outlaw.
Belle Starr was 14 years old in 1862. Dr. Quinn is set in 1868 and later.
Belle's horse would not have been removed from the barn and left sitting in town saddled and ready for escape.
The green Vaseline glass candlesticks on Dr Mike's dining table are from the 1930s.