Skeates and Cardy share a weird but entertaining tale in Teen Titans 32 (March/April 1971), which is largely a two hander for Kid Flash and Mal Duncan.
Speedy, Lilith and Wonder Girl are also in the story, working with Mr. Jupiter as he performs a time theory experiment which backfires, and winds up sending Mal Duncan into the prehistoric era. Kid Flash, having some experience with travelling through time using his own powers, heads back to find and rescue Mal.
Before Kid Flash shows up, Mal winds up in a fight with a teenage caveman, after the girl he is interested in takes a liking to the Titan. The fight ends with the caveboy accidentally falling to his death. Kid Flash has shown up by this point, and tries to bring Mal back to the present, but they discover that, because of the caveboy's death, reality has been altered.
The present now looks sort of medieval and mystical. They head to a castle, which belongs to Jupiterius, who has the body of Mr. Jupiter. Superman, Batman, Flash and Green Arrow make cameos, in altered forms, as servants of Jupiterius, and later Speedy and Lilith are revealed as his agents as well, though in the clothes we are used to seeing them in.
Jupiterius makes Kid Flash and Mal prove themselves in a test, to open a door by piercing the lock with an arrow. Kid Flash pulls off the amazing shot, and the door opens, but what is on the other side is not revealed until the next issue.
Oh, and I guess I should say the cave boy in this issue will later be known as Gnarrk.