Doing It for the Art: The production of "Someone to Watch Over Me" went to ridiculous lengths in order to realistically depict a man playing and composing music on an old and beat-up piano. Having a basic knowledge of how to play a piano was a casting requirement for Dreilide Thrace - this enabled the crew to film from any angle without having to hide the actors' hands or use a "stunt performer." Because the prop piano was intentionally left out of tune and due to the specific acoustics of the set, any re-creation of the sound in post-production would've sounded incredibly different (and thus rather fake). As a result, composer Bear McCreary sampled every note on the prop so that he could later duplicate the sound of that exact piano in that exact room. Once they actually arrived at post-production, it was pointed out that production recordings of the prop piano were in mono, while any music re-created would be in stereo. What did Bear McCreary do? He rerecorded every piece of music played by the actors down to the last note, syncing his recordings with the actors' exact hand movements at the same time. The final product is just simply amazing.
Executive Veto: SciFi Channel explicitly told Ron Moore and David Eick that they couldn't show any live people on board the Olympic Carrier when it's destroyed, so they didn't. However, every time the ghost of the ship is brought up it usually comes with a pointed reference that, yes, there were people on it when it was shot down even if we didn't see them.
Fake American: Jamie Bamber, who plays Lee/Apollo, is British (though his father is American and he claims to have been raised partly in Detroit). Most of the cast, though, are Canadians, so they sound almost like Americans. However, Canadian English occasionally creeps in, such as Tricia Helfer's pronunciation of "resources" as "ree-zources." At the end of Final Cut, Lucy Lawless, who otherwise used her natural Kiwi accent, affected a Canadian/American accent for the Number Three in the cinema.) One could disagree with them being fake Americans as none of the characters are "American" (or even Earthican).
Word Of God (on the Razor commentary) says that Jamie Bamber only did the accent because it would have been too weird for him to have a different accent from his screen father, since he already doesn't look anything like him.
Fake Mixed Race: Hera's actress isn't half-Cylon. Interestingly, though, the infant version was the one who was half-Asian.
Fan Nickname: The Tattooed Pilot's unofficial call sign among fans is "Dragon" due to his dragon tattoo; Layne Ishay is "Nurse Bedside Manner" for her notable lack of any; President Rosylin is Madame Airlock for her penchant of throwing people out of them.
Poor Man's Substitute: Beautifully subverted. The role of Laura Roslin was written for Mary McDonnell, but the producers never imagined they'd actually get her. Obviously, McDonnell said yes.
"Hero" and "The Defector" (the writing of the latter, ironically, credited to Ron Moore) both revolve around someone in a small ship being chased by the enemy and seeking refuge under questionable circumstances. In both cases, subsequent review of the data shows that the enemy was shooting to miss, and as a result the crew realize that the enemy was allowing the fugitive to escape to further their own sinister motives.
"A Measure of Salvation" and "I, Borg" both involve the crew capturing a member (or members) of the enemy, and then plotting to return him/them to their own kind with a genocidal virus.
Screwed by the Network: While Sci Fi was nothing but supportive of the show during its production, they had some strange ideas when it came to broadcasting it, such as allowing the UK to air the first season six months ahead of North America, splitting the DVD releases of seasons two and four in half, fiddling with the show's time slot for the first three years, mandating the opening sequence be curtailed to make room for more commercials (this one was eventually vetoed by a fan outcry), and airing the two halves of season four a full year apart to eke out a de facto fifth season.
Edward James Olmos contributed a ton of these through ad libbing, particularly one memorable scene were in a fit of grief and rage over Starbuck's death he destroys the model ship Adama had been repairing for the past three years. This was a case of Truth in Television because Olmos himself was genuinely upset and angry over Katee Sackhoff's departure from the cast (or so he believed). The ship was a loaner from a maritime museum and was worth over $100,000, unbeknownst to him. Luckily, it was insured.
After a heated fight between Gaeta and Starbuck, she storms out, and Alessandro Juliani (playing Gaeta), without turning around to look at her, throws in a snippy line.
Gaeta: So I guess a pity frak is out of the question, then?
An NBC pilot called The 17th Precinct. Created by Ronald Moore, and starring Battlestar Galactica and Caprica alumni such as Esai Morales, Jamie Bamber, James Callis, and Tricia Helfer, about the titular precinct in a world with magic instead of science. It ended up getting passed over by NBC. Fortunately, it has now been leaked online in all of its what-might-have been glory.
If what Ronald D. Moore says on the podcast commentary for "Kobol's Last Gleaming Part 1" is to be believed, how he originally wanted it to end was for Baltar to go down a long dark tunnel in the ruins on Kobol, at the end of which he finds Dirk Benedict, who introduces himself as "God". Oh, and Baltar also hears an actual Jimi Hendrix recording playing during all this, and when "God" asks him if he recognizes the tune, he says "yes". And Moore claims to have had absolutely no idea what any of this was supposed to have meant, but the other PTB were barely able to talk him out of it.
The Wiki Rule: There's the Battlestar Wiki, which can be found here.