Shiro Hamaguchi (Final Fantasy) composed the music for the first 3 seasons. Cher Watanabe was responsible for Kira Deco's. Wataru Maeguchi was responsible for that of the movie and Happiness.
No Export for You: The anime and the toys were not released in the States due to similarity issues with Webkinz; both Sanrio and Sega could get sued for it. note And even if that problem didn't exist, America wouldn't even think of licensing child-oriented, Magical Girl shows. But it's released in much of Europe and Asia.
The Sunshine dubs are based strictly on the Japanese home video release, which means that any insert songs are removed, as having them remain would mean additional royalties would have to be paid to the parties involved. Somewhat compensating this is the fact that some of the scenes with insert songs are available in Youtube and Nico Nico.
The toys made it to Brazil. The same can't be said of the anime.
Italy and possibly Greece only aired the first series. France so far hasn't moved past Twinkle.
Too Soon: Episode 50 of Twinkle was to air on the 12th of March, 2011, a day after the 2011 Tohoku earthquake struck. This episode and the one after feature intense scenes of fighting and destruction (albeit in a very fantasistic fashion that probably wouldn't evoke the earthquake), and so it was one of the many anime to be postponed to a week later.
Trolling Creator: Kazuyuki Fudeyasu (in charge of series composition, i.e., decides what the story is) trolled older audiences big time when the true nature of Kira Deco's villain was revealed.
What Could Have Been: During the pitching for the first series, Ruby was meant to be a polite and tidy character. Then Sanrio and Sega decided to alter her personality to become scatterbrained and naughty, which is reflected by the jewel she is based on.
Pre-airing promotional material for Sunshine often depicts Shouko and Labra together, which suggests that they were supposed to have some significant relationship. They hardly interact in the finished product.
The anime was intended to end with Kira Deco, but a fifth season got made due to Kira Deco's poor reception.
Kira Deco was planned to have its soundtrack officially released sometime during the anime's airing but alas, that never happened.
Cross Dressing Voice: In the human department we have Akira Nanase, Nicola, Midori Akagi and Taira Izumi. As for Sweetspets, there is Park, DonaDona and Chocolat. And among Jewelpets, there's Tour, Nephrite, Titana, Chite, Rald, Kohaku, Yuku, Tata, Kris, Io, Alex and Brownie.
Dawson Casting: Averted with Princess Mana, who's played by the 2004-born Mina Ashida.
The Other Darrin: Jewelina, Sango, Milky, Aqua, Alex and Rin. Alma is a strange case, because she got a different voice when she disguised herself as Laiya.
Ruby is Elsa. No amount of Flat Whats is going to diminish the WTF-factor that comes with that knowledge.
Anna is here too; she's Labra.
Every protagonist is voiced by the same actress. That doesn't sound like anything special by itself, but then you compare Akari and Kanon, who couldn't be more opposite if they tried, and you can't help but be impressed.