Due to the violent content of some episodes, the series has never been broadcast in its entirety outside of Japan.
The animation team was very nervous of how Tove Janson would react when they showed her the first animation tests.
They needn't be, since Toves reaction was an astounded "They're alive" (meaning her characters).
When the series was broadcast in Sweden, Tove Jansson insisted that the original Finland-Swedish dub be used, rather than dubbing the show in standard Swedish. Because of this, the variety of Swedish commonly spoken in Finland is sometimes referred to as "the Moomin language" in Sweden. Generally, the Moomin family is always played by Finland-Swedes in Swedish localizations and adaptations, but not always the supporting cast. The dub of [Moomins and the Winter Wonderland (2017)] was not dubbed by Finland-Swedes and meet with backlash because the audience did not think they sounded like the Moomins.
Benny Törnroos was chosen to perform the theme song for the Finnish and Swedish dubs because the producers wanted someone who could sing in both languages.
Desbite the voice being very masculine, The Groke is a female.