Before the series, Culp had written a pilot script in which he would play a James Bond-type American spy. He showed the script to Carl Reiner who then recommended him to Sheldon Leonard. The script was eventually produced as the episode "The Tiger".
The show was not aired on certain NBC affiliates in the south due to the fact that it dared to show an African-American actor (Bill Cosby) on the same level as a white actor (Robert Culp). This also included the original Star Trek series where a black actress (Nichelle Nichols) and Asian actor (George Takei) are seen as part of the U.S.S. Enterprise's crew.
According to a TV Guide interview with Culp, Cosby was originally uninterested in doing the series and insulted the producers during his audition. Culp mediated between them and helped Cosby get cast.