Award Snub: Heartcatch Precure! The Movie: Fashion Show in the City of Flowers?! was nominated for the Kidscreen Award along side Zhu Zhu Pets: Quest For Zhu and Wapos Bay: Long Goodbyes, the latter of which won. (Want to watch the winning movie? Well, good luck with that!) No word, though, if it did better against Zhu Zhu Pets.
Ensemble Darkhorse: The fandom seems to have quite a fixation on certain supporting characters, particularly Sayaka and Kenji. The latter gets quite a bit of fanart of his imagined alter-ego from episode 21, Cure Fire. There's also a lot of fanart of his mom.
Heartcatch is this among Pretty Cure in general, to the point of Tough Act to Follow. There's is a perception that the franchise entered a Dork Age after Heartcatch that only ended after Go! Princess Pretty Cure...and that's not because Princess is as good as Heartcatch, it's just better than anything that came after it.
Heartcatch can be said to be the Precure with the most solid, well loved main squad ever. Itsuki has always been a solid all-rounder, but Erika usually gets praised as the funniest Precure ever, while Yuri gets praised as the most Badass amongst all Precures. Meaning that this team really is a group of Darkhorses.
"Heartcatch Precure!: The Movie" was apparently popular enough in France that it was simple dubbed into French, and has a surprising number of Fans in the West, which begs the question why no Movie Theater/TV Station wants to air that anime film.
The show in general has quite a few Western fans for just being a great show.
Growing the Beard: The series really began to take off after episode 8, which provided great character development.
With his fluffy hair, Kenji Ban could be easily mistaken for a shounen anime character. Two years later, Yoshihiko Umakoshi, character designer for Heartcatch, went on to work on an actual shonen anime.
Unintentionally speaking, Cure Blossom and Cure Marine, inclusing Coffret and Chypre respectively reminds some fans of Robotboy and Robotgirl from Robotboy.
There is fanwork pairing up Tsubomi with every other Cure in the series, a number of supporting characters and a couple of villains. A few fans even joked that the series was actually all about her building a harem.
Itsuki, arguably, given how popular she is with the ladies.
The Heart Seeds needed to save the Heart Tree — the fairies poop them out. Um, ew. This leads to rather humorous Oh Crap! (no pun intended) moment in episode 28 when they realize what was about to happen after saving so many Heart Flowers at one time. Thankfully, after a while the Heart Seed sequence gets cleaned up just a little, though you still know they're pooping.
Throw the Dog a Bone: Infuriatingly denied. Even though Yuri has to cope with a machine-gun volley of traumatic revelations and events (her fairy partner dies forever; Saabaku is her father; Dark Precure is her genetic little sister and was created by her Brainwashed father specifically to kill her, only to die at Yuri's hands; her father leaves Yuri to comfort Dark Precure in her dying moments, her father is killed in front of her by the Big Bad) and still manages to save the world, she gets no reward or compensation for the losses she's suffered. It's an incredibly Bittersweet Ending for her character, extremely so by the standards of kids' anime.
Trailer Joke Decay: Yuri's transformation sequence would have been much more badass and surprising if it wasn't the only damn thing shown in the next episode preview.
Viewer Gender Confusion: It's not uncommon for people to mistake Itsuki for a very cute boy upon first watching the series. If Tsubomi is any indication...