The song that the choir sings, "Welcome," is a song from an actual recording of the real People's Temple Choir.
Madge Sinclair plays LeVar Burton's mother. She had previously portrayed the older Kunta Kinte's wife in Roots (1977), and would go on to play Burton's character's mother on Star Trek: The Next Generation (1987).
Powers Boothe's height and build were very different from the height and build of the real Jim Jones. Boothe was 6' 2" with an athletic body type. Jones was 5' 8", and all the way through his life he was overweight with a large belly.
Despite receiving prominent billing, James Earl Jones only appears in one short scene in part 1 of this miniseries, and does not appear at all in part 2.