- In 1971, Karns and his wife moved to Ajijic, Mexico and opened the English language Lakeside Little Theater where he produced and directed plays for 30-years.
- Appeared on a play in 1953 called "Flame-Out." A comedy-drama written and directed by Alan Mowbray. The play was presented for nearly a year at various Air Force bases enacted by an all-soldier cast. It starred Karns, Jack Lord and Harry Carey, Jr., all who received excellent reviews for their performances in Flame-Out.