- Crossdressing Voices: Kale, Shallot, Hickory, and Twirl are all voiced by females.
- Dub Name Change: When Viz Media brought the Manga to the States, they officially changed the names of the main characters. Nobi-Nobi did the same in the French translation while changing the title.
- Chima (Japan) > Clover (US, France)
- Tabi-Usagi-San (Japan) > Rambler / Bramble (US) > Buster (French)
- Meru (Japan) > Mallow (US) > Mellow (French)
- Gaku (Japan) > Kale (US) > Gabi (French)
- Haru (Japan) > Shallot (US) > Scoot (French)
- Hirari (Japan) > Hickory (US) > Mermoz (French)
- Charaku & Kururi (Japan) > Cinnamon & Twirl (US) > Curry & Noisette (French)
- Hohho (Japan) > Professor Hoot (US) > Professor Houhou (French)
- Line to God: Sayuri Tatsuyama has a Twitter account where she posts illustrations of her characters and gives some updates about her manga career and life.
- Keep Circulating the Tapes: As of 2016, there is no DVD release of the series due to Group Tac has since gone bankrupt back in 2010 and after some of its staff left the company and formed Diomedea back in 2006, resulting to the said bankruptcy and the closing of the animation studio.
- The Merch: During the manga's run from 2005 - 2008◊, there was tons of merchandise◊ promoting the manga and later the anime adaption in 2007.
- Milestone Celebration: In August 2015, Comiiket 88 sold a Happy Happy Clover Anthology submitted by various artist and fans of the manga in Japan. The anthology also contained artwork celebrating the 10th Anniversary of the original publication of the manga on Ciao Magazine.
- No Export for You: Both of the Nintendo DS games◊ are only in Japan. Meanwhile the anime adaptation, hasn't even gotten a dub despite the manga getting translated in 2009.
- The manga did get a French release in 2016 by Nobi-Nobi.
- Pigeonholed Voice Actor: It appears Mallow's voice actress Tae Okajima would also voice Kotonoha and Cinnamon who are also very shy characters and very sensitive.
- Shrug of God: Sayuri Tatsuyama herself admits that she finds Rambler and Clover to be a cute couple.
- Relationship Voice Actor: Yumiko Kobayashi and Takehito Koyasu would later be talking to each other again in Soul Eater with Yumiko as Black Star and Koyasu as Excalibur
Trivia / Happy Happy Clover