"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.
Rob Tapert really disliked "The Cave Of Echoes" from Season 2. He didn't mind having to do a Clip Show, but he cited this as being a particularly weak example due to how cheap it looked (the featured characters just walking up and down a cave set). Later clip shows on both shows had more inventive framing devices as a result of his dissatisfaction with this episode.
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).
Edited for Syndication: For a couple years, the show was rerun in a late-night slot on the Hub Network (now Discovery Family). The network aired a TV-PG disclaimer about moderate violence. For the most part, episodes were generally shown as they were on the Sci-Fi Channel, with only minor edits here and there (such as the leg breaking scene in "Armageddon Now, Part 2" and some sexual content in "Stranger And Stranger").
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, and this situation was never a problem for the other channels that would rerun the series.)
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. Many of the suggested ideas (using Young Hercules, trapping Herc with the Sovereign) were done in the actual episodes.
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.
"Be Deviled" concerns an old enemy of Hercules's coming Back from the Dead to get revenge on him and try to keep the sister he left behind from going down the same dark path he did. However, the featured villain was originally going to be Callisto herself, and she would learn that her sister wasn't killed in Cirra after all. This was meant to make up for a mistake from the "Armageddon Now" two-parter, which depicted the deaths of Callisto's parents but left the sister completely unaccounted for; it would've also tied into the Heaven/Hell material that was building up on Xena at the time. However, it was decided that something so important to Callisto's backstory should've been done on Xena instead of Hercules, so a one-off male villain was used instead.
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.
Herc's two half-brothers Ares and Iphicles bore an awfully strong remarkable resemblance to each other, despite not sharing any blood relation. (Out of universe, both were of course played by the late Kevin Smith.)
In one episode, Aphrodite turns a pig named Katherine into a human (It Makes Sense in Context). Catherine's human form is played by Alexandra Tydings, who plays Aphrodite. The goddess of love even compliments Catherine's attractiveness.
Besides Iolaus, Michael Hurst played both Orestes and the Widow Twanky. Orestes is Iolaus' half-cousin and the two looking alike is a plot point for both episodes he appears in. Instances of something "familiar" about the Widow Twanky, though, is played as pure Lampshade Hanging. He also played Charon, although it's harder to tell under the prosthetics.
Before playing Xena, Lucy Lawless appeared as Lyla, the human girlfriend (and then wife) of a centaur. In "Outcast" (which was produced after Xena was established), Salmoneus notes the similarity.
Lawless also played an "Amazon" in the first Legendary JourneysMade-for-TV Movie. These are different Amazons than the ones which come up later in the Herc/Xena verse. She has sex with Zeus (not knowing he's a god).
Lisa Chappell played three different characters over the course of the series—Lydia, Dirce, and Princess Melissa—with a lampshade hanging when Dirce met Melissa in "Hercules on Trial" and commented that she was "uncommonly beautiful".
Those who only remember Renee O'Connor as Xena's sidekick Gabrielle may be surprised to see her playing a totally different role in the second Hercules movie, "Hercules and the Lost Kingdom," as a young Trojan princess who is quite smitten with our hero.
Joel Tobeck played a villain of the week in a Season 2 episode. He later returned to play Strife. After Strife was killed, he turned up as cousin Deimos. The resemblance between the two gods was Lampshaded in "Fade Out:"
Ares: They look enough alike, don't you think? Deimos: Do not. I'm taller, and he's dead.
Erik Thomson played King Daulin in the Season 1 episode "The Vanishing Dead". He would later go on to play Hades for the rest of the show's run, in four seasons of Xena: Warrior Princess, and in one episode of Young Hercules.
A number of the minor villains are played by the same actors. A slaver from the season 1 episode "March To Freedom" returns as the brother of the defeated warlord Demetrius in Season 2 episode "Cast A Giant Shadow." Similar, but more apparent examples are the two centaur twin brothers who both seek to kill Hercules, one for his wife, the other to avenge his dead brother.
Also, actor Glenn Shadix played both the giant Typhon and his twin brother Typhoon.
Robert Trebor, Salmoneus, shows up in the second Made-for-TV Movie as Waylon, a slave who runs away from his mistress to become the slave of Hercules, who frees him.