was any racially derogatory word used in the musical?
The word "niggers".
Show Boat
The show has generated controversy for the subject matter of interracial marriage, the historical portrayal of blacks working as laborers and servants in the 19th-century South, and the use of the word "niggers" in the lyrics (this is the first word in the opening chorus of the show). 
the orginal broadway production of oklahoma opened on broadway on UNANSWERABLE what is show boat? It is a musical in two acts. is this based on someone's literary work? It is based on Edna Ferber's best-selling 1926 novel of the same name. what does the storyline depict in this musical? It follows the lives of the performers, stagehands and dock workers. what are the names of the characters featured in this? UNANSWERABLE was it adapted into a film? It has been adapted for film three times. what are some of the themes of this? UNANSWERABLE
wiki:1855261
Show Boat [SEP] The word "nigger"
The show has generated controversy for the subject matter of interracial marriage, the historical portrayal of blacks working as laborers and servants in the 19th-century South, and the use of the word "niggers" in the lyrics (this is the first word in the opening chorus of the show). Originally the show opened with the black chorus onstage singing: In subsequent productions, "niggers" has been changed to "colored folk", to "darkies", and in one choice, "Here we all", as in "Here we all work on the Mississippi. Here we all work while the white folks play." In the 1966 Lincoln Center production of the show, produced two years after the Civil Rights Act of 1964 was passed, this section of the opening chorus was omitted rather than having words changed.