One of the great continuity glitches - Sisyphus was *also* King of Corinth, in the episode where Herc had to retrieve him, after he had switched places with a young bridegroom. Early 2nd season - "Highway to Hades," aired 11/20/95, and Ray Henwood played Sisyphus, King of Corinth. Only proble was - exactly one week earlier, on 11/13/95, Ray Henwood had guested as King Sisyphus of Corinth ....on XENA "Death in Chains," where he tried to pull the same stunt by imprisoning Celesta.
(And if you want to get *really* technical, someone was King of Corinth while Xena was besieging the city in "Past Imperfect" - Couldn't have been the young Jason, since he woul simply have gotten his friend Hercules to come kick Xena and Borias's butts!)