To counteract the buoyancy of the air-filled breathing skin, paladin loads two bags with rocks, when he swims the bags float.
Throughout the episode, set in circa 1870's, Paladin wears what is clearly a factory-made, black, V-neck, buttonless undershirt. Such a garment wasn't manufactured until the 20th century.
Although credited as Jonah Quincy, Paladin and Mr. Barton call the Harry Carey Jr. character "Jonas".