Queen Latifah (The Wiz) and David Alan Grier (The Cowardly Lion) previously played Aunt Em and Uncle Henry in The Muppets' Wizard of Oz (2005).
Stephanie Mills played Dorothy in the original Broadway Production of The Wiz in 1975. She returned to Broadway in the role in a 1984 revival of the show. In 1989 she had a #1 R&B Billboard chart hit with a new version of the song "Home."
Toto does still make an appearance.
Uzo Aduba wore a blonde curly wig when portraying Glinda in early promos. By the time the special actually aired, Glinda sported brunette braids instead, after the crew realized that letting Aduba show off her natural hair color would provide a stronger expression of African-American beauty.