Complex sentence: Cleavon Little's guest appearance on "All in the Family" led to him being cast in "Temperatures Rising", which in turn led got him a role in the Mel Brooks comedy film "Blazing Saddles" (1974).
Split into simpler sentences: Cleavon Little's guest appearance on "All in the Family" led to his being cast in "Temperatures Rising". This in turn led to his being cast in the Mel Brooks comedy film "Blazing Saddles" (1974).