In the novel, Leto and Ghanima are 9. For the miniseries, they appear to be nearly twice that age, so they could be played by adults.
Despite the title, only the second and third parts are adapted from the novel "Children of Dune" (the third novel in Frank Herbert's "Dune" series). The first part is based on the second novel, "Dune Messiah".
According to interviews, Alice Krige was John Harrison's first choice to play Jessica in Dune (2000), but was unavailable. However, Saskia Reeves had to back out of this miniseries because of pregnancy, so Krige was re-offered the part.
Alec Newman (Paul Atreides) and Julie Cox (Princess Irulan Corrino-Atreides) were a real life couple during filming.