This show was genius. Robt.Conrad did all his own stunts. You can see the scene where he broke his back & needed to recover for weeks afterward. They kept and used that very footage in a barroom brawl (one of MANY in the show) where (IIRC) he swings from a wagonwheel-chandelier in a saloon, only to land supine on a table below.
Ross Martin died like the entire cast & crew of THE WARLORD (with John Wayne) did - cancer from radioactive dirt trucked in from Nevada by producer Howard Hughes.