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.
Susan Sarandon, who plays Princess Wensicia Corrino, is nearly 30 years older than Julie Cox, who plays her sister Princess Irulan. In the books, however, Irulan is the older of the two sisters. Sarandon agreed to take the role because she was a huge fan of Frank Herbert's "Dune" novels.
Brian Tyler's music for this miniseries is used regularly in movie trailers, e.g. The Golden Compass (2007), Indiana Jones and the Kingdom of the Crystal Skull (2008) or Master and Commander: The Far Side of the World (2003).