Acting for Two: "Yes, Virginia, There is a Hercules" had Kevin Smith portray both Ares and show writer Jerry Patrick Brown. One particular shot used Double Vision. Kevin Smith also played Hercules' full human brother Iphicles.
Michael Hurst played Iolaus and a look-alike distant cousin in "King For A Day" and "Long Live The King." The one time he played Iolaus and Charon in the same episode was "Highway To Hades." He also played Widow Twanky and while Iolaus never appeared in those episodes, Hurst did play a one-scene homeless man role in Twanky's last appearance.
Directed by Cast Member: Kevin Sorbo directed "The Apple" and "War Bride." Michael Hurst directed "Mercenary," "...And Fancy Free," "One Fowl Day," "Faith," "Somewhere Over tinbow Bridge" and "Greece Is Burning."
Recurrers Bruce Campbell and Robert Trebor also had turns at directing (seven episodes and one, respectively).
Missing Episode: By the fifth season, the Sci-Fi Channel acquired the rerun rights... but not for the soon-to-be produced, eight episode long Season 6. Reruns continued well after the Grand Finale premiered, but Sci-Fi never aired those last eight episodes. (Fortunately for fans, Season 6 was released on DVD.)
Name's the Same: In universe example- Traicus was apparently a very popular name for warlords as several were mentioned or shown.
Nemesis was played by at least three different actresses - the last of which after she was Brought Down to Normal.
Reality Subtext/Written-In Infirmity: "Yes, Virginia, There Is A Hercules", a clip show in which the staff of HTLJ try to work out what to do after Kevin Sorbo goes missing, was written when Sorbo fell seriously ill and couldn't film.
Romance on the Set: Kevin Sorbo met his future wife Sam Jenkins during the filming of "Prince Hercules." Presumably, this was part of the reason why she was brought back only a handful of episodes later as Serena the Golden Hind.
Throw It In: During script readings, the writers and producers were very open to suggestions from Kevin Sorbo, Michael Hurst and main guest actors. This extended to during filming, such as the "Doe, a deer, a female deer" exchange in "Encounter."
What Could Have Been: Another spin-off with Autolycus as the lead? It was apparently briefly considered, but among those that nixed it was Campbell himself (as he felt it would make the character too much of a good guy and less of a wild card).
Waylin the slave from The Lost Kingdom TV-Movie was originally going to be brought back as a recurring character. However, it was decided there was nothing else that could be done with the character. (Producers liked Robert Trebor, though, so Salmoneus was created in Waylin's place.)
Following up on the Norse gods two-parter, Paul Robert Coyle had hoped to do a spin-off or at least a sequel story seeing Thor journey to Greece.
Originally, the script for "Unchained Heart" would've seen Xena die in a Heroic Sacrifice where Redemption Equals Death. However, Herc's companion series at the time (Vanishing Son) was being cancelled and the studio wanted a replacement. The fact that production took a liking to the character didn't hurt, either.
Vanessa Angel was originally cast as Xena, but she got sick and was unable to fly out for filming. Melinda Clarke (who would play Velasca on the spin-off) was also in the running at one point.
Rob Tapert has said that the "Twilight of the Gods" storyline from Xena would've been done concurrently on Herc's sixth season had it been a full season and not eight episodes.
Early into the fourth season, Kevin Sorbo suffered some health issues. To accommodate him, the writers put more focus on Iolaus, produced "Men In Pink" (an Autolycus/Salmoneus episode), utilized Autolycus more and produced three additional Young Hercules episodes. Sorbo actually appeared in all but "Men In Pink" during this period, but his screentime was reduced from its usual length - only increasing the more he recovered.
During a Crossover with Xena, Michael Hurst broke his arm while filming a fight scene. Iolaus' arm was subsequently injured in "Cast A Giant Shadow" and was seen in a cast for a couple episodes.