The decaying Southern mansion seen on the series was the Tara set from Gone with the Wind (1939), which stood on the back lot at Desilu Studios (formerly Selznick International Pictures). The facade was sold and moved to Georgia in 1959.
In the original story on which the pilot episode was based, the hero was simply called Derringer. The first name, "Yancy," was added specifically for the TV series, which was produced by Desilu Studios.
The series was co-owned by the husband-and-wife team of creators Richard Sale and Mary Loos, producers Warren Lewis and Don Sharpe, and Jock Mahoney, with Desilu handling production. The series' sponsor, Johnson's Wax, had committed to funding a second season, but negotiations with its network, CBS, stalled when the network insisted on taking part ownership. The star and creators refused, and CBS did what no bad guy could: killed Yancy Derringer.
The "original" G.I. Joe, Joe Colton, was named after John Colton, the city administrator who gives Yancy his assignments in the series.
The character on whom the series was based first appeared in the pulp magazine story "Derringer" by series co-creator Richard Sale. The story appeared in the 3/11/39 edition of "Detective Fiction Weekly".