Actor Allusion: "I've always liked Klingon females. You've got such... spunk." This is spoken by a Female Q to Lt. Torres in "The Q and the Grey." Not only did the actor playing Q (Susie Plakson) previously play a Klingon on TNG, she played a Klingon-human hybrid, like Torres.
Little did Rick Berman suspect that when he cast the star of Night of the Comet to be his Number One, he had unwittingly spawned Winnebago ManIN SPACE. Not long into VOY's run, Robert Beltran (Chakotay) stopped playing Mister Nice Guy and openly expressed his loathing of the show's plot, his co-stars (he only signed on to act alongside Geneviève Bujold), the producers, himself for playing such a formulaic role, and most of all you for watching it. His co-stars fired back in separate interviews, and the showrunners publicly told him to muzzle it, but they refused to grant Beltran the satisfaction of killing him off. Beltran saw out the entirety of his contract. (Years later, Beltran claimed on Reddit that the public took his "flippant" comments too seriously and that his "overall" experience with the show was positive.) This would not be the last time actors rebelled against Brannon Braga - see Enterprise.
Garrett Wang was somewhat lethargic himself, which is part of the reason why Harry Kim was never promoted. The producers didn't fire him, either (for publicity reasons), but he pointedly did not direct a VOY episode despite many requests. Although, he wasn't nearly as cynical about the show as Beltran and there are no reports of him being a jerk to his coworkers.
Remember how an additional cast member and second pilot revitilized Deep Space Nine? Well, lightning managed to strike twice, but Seven's arrival only aggravated the prexisting tensions in the cast. Mulgrew was reportedly ticked about the show's focus shifting toward Seven of Nine, not so much out of dislike for her svelte usurper (she admitted the character saved VOY from cancellation) as resentment over sacrificing time with her family for a TV series Janeway no longer starred in.
The Danza: Kate Mulgrew was hired as a last minute replacement for Nicole Janeway (played by Geneviève Bujold) and she asked to have the first name changed to her full first name, Kathryn. Janeway's first name had originally been Katherine (note the different spelling) while the series was in development, but was changed to Nicole when the French-Canadian Bujold was cast in the role. The creators asked Mulgrew which of the two she would prefer, and she opted for a slightly altered version of the originally planned name.
Several scenes in the pilot had to be reshot because the studio vetoed Kate Mulgrew's hairstyle.
The divisions between the Starfleet and Maquis officers were originally going to be more pronounced, but after the pilot, the network asked for this to be changed. The divisions were made more minor in Season 1 and largely ignored afterwards.
Fake Nationality: Garrett Wang is Chinese-American, while "Kim" is a common Korean name (The character was born in South Carolina).
Fan Dumb: According to Wang, the introduction of a female Captain was met with a parade of angry letters, mostly from people whom we might classifiy as "MRAs" in today's parlance.
Chakotay is often called 'Woodentop' (or variations thereof) due to his acting skills (or, more charitably, the limits the scripts imposed on the skills he had). More affectionate nicknames one might hear include Chak/Chuck, Commander Tat-face, and maybe Commander Studmuffin.
Neelix has one too. But it's not really repeatable in polite company... (HINT: It has to do with how useful his mind is, and what his head looks like...) SF Debris prefers to call him "Hedgehog," or "S**thead."
Harry Kim is called, both by people who hate and love him, "The Dweeb."
David Clennon, aka Palmer, played a Cardassian scientist.
The Other Darrin: Alice Krige was brought back to play the Borg Queen for "Endgame". Susanna Thompson originally auditioned for the Queen in First Contact, but came back when Krige was unavailable to shoot VOY.
Promoted Fanboy: Unlike most Star Trek actors, Tim Russ came into the series as a full-fledged Trekkie. He would get into arguments over how a Vulcan would behave, but still his portrayal of Tuvok was likely the best Vulcan performance since Leonard Nimoy and Mark Lenard. In fact, Russ' first try at getting into Trek was auditioning for Geordi La Forge in Star Trek: The Next Generation. He would eventually do a small guest star role there (funnily enough, as a villain who gets nerve-pinched) and on Star Trek: Deep Space Nine, as well as play a bridge officer on the Enterprise-B in Generations.
Real-Life Relative: Q's "teenage" son was played by John DeLancie's actual son Keegan DeLancie. This was apparently somewhat of an accident; Keegan happened to be among the actors being considered for the role and the producers made it clear they didn't want him cast just for the joke. As it turned out Keegan won them over on the part and the existing Father/Son dynamic only made the episode better.
Science Marches On: Distant Origin has a species of reptilian aliens, one of whose scientists discovers the remains of a Red Shirt from a previous episode. They express surprise that the being, whom they note is a distant cousin of theirs, is an endotherm (warm-blooded). This was in 1997, prior to the knowledge of dinosaurs being probable endotherms was common knowledge.
Star-Making Role: Seven of Nine for Jeri Ryan. While still busy, for a time in the late 90's she was everywhere.
Due to the cost of building VOY's bridge, converting the old TNG sets, reshooting the scenes shot with Geneviève Bujold and Janeway's hair debacle, some very pricey special effects scenes and a substantial amount of location filming, "Caretaker" had a final budget of US$23 mil, making it the most expensive episode in the history of Star Trek. When adjusted for inflation, it proved even more expensive than The Wrath of Khan. A running gag on-set was, "I wonder if we'll get this pilot shot before the series is over."
There was a lot of infighting amongst the show's staff. Both cast and the writing crew, not to mention the executives at UPN. Robert Beltran and Ron D. Moore are among the better known examples of internal dissent.
Braga did say that if Voyager was up to him, the show would have frequently been like the fan favorite episode "Year of Hell": enemies on all sides, dwindling resources, and crewman pushed to the ends of their rope.
At the end of season three, either Harry Kim or Kes was slated to be killed off to make room for new character Seven Of Nine. Neither were killed off in the season finale, but the more likely candidate, Harry Kim, was seriously injured so that he could die in the fourth season premiere. Between seasons, Garret Wang ended up listed on Entertainment Weekly's list of 100 Hottest Celebrities, and the Executives mandated that he had to stay — so they wrote out Kes instead. This is especally ironic given Rick Berman's mandate that the alien characters be more interesting than the human ones.
According to Jennifer Lien, she had recently given birth before her audition. The execs were thus floored when her breasts shrank down to normal size.
The ending of "Basics" originally had Maj Cullah and Seska's baby die, and Seska escaping with Lon Suder in tow. As it turned out, the exact opposite happened. The writers wanted to close the book on the Kazon due to plummeting ratings. In addition, Jeri Taylor wasn't fond of Suder's character; hence his Redemption Equals Death arc.
"Non Sequitur" was originally supposed to feature Counselor Troi as the one grilling Harry Kim in the alternate timeline instead of yet another random Admiral. The creators were unable to get Marina Sirtis on short notice. (She did appear with Reg Barclay a few seasons later.)
Before getting the role of The Doctor, Robert Picardo originally auditioned for the role of Neelix.
Jeri Ryan has said that she read two different scenes when she auditioned for Seven of Nine. One was the rather notorious Do You Want to Copulate? scene, which ended up being filmed (and she admits to hating it to this very day.) The other was apparently a really beautiful, touching scene where Seven first experiences laughter, and she seems to honestly regret that scene never made it to film. Other actresses who auditioned for Seven were Hudson Leick and Claudia Christian.
When the Borg tactical cube was in the planning stages, Doug Drexler sketched up a "pyramid" version; this was a joke, to reference the first UPN logo, which consisted of a circle (the Borg sphere), a triangle (the "Paramountain"), and a square (the Borg cube). It was only a joke sketch though.
Garret Wang campaigned to be the first homosexual in Starfleet, but the execs said no way. (Technically, Jadzia Dax was the first bisexual in Starfleet, owning to her species' gender-flipping attributes and long lifespans.) Wang's own view is that Harry's a closeted gay man who pursues unattainable women as a means of avoiding his feelings for Tom. Later, Dominic Keating came away with a very similar impression of his own character's psychological makeup — see Enterprise.
Robert Beltran jokingly said in one interview that Chakotay was a homosexual. For fans of slash fiction, this is the last bit of evidence needed to confirm that Chakotay and Paris are bitter ex lovers, and that Seven is merely his beard.
Word of Saint Paul: Second-hand sources from Trek conventions has it that Kate Melgrew (Captain Janeway) believes her character is bipolar due to the inconsistent characterization. There's no real way to corroborate it, but we do know that Mulgrew found the Captain's waffling to be wearisome on her thespian talents.