http://www.tmz.com/2014/11/17/the-simpsons-mr-smithers-black-creator-matt-groening-mistake/

Producers made a mistake with the 1st episode.
Read more at http://www.hitfix.com/tv-tattle/fired-today-boss-reportedly-invoked-survivor-in-creating-a-backbiting-workplace#Pjbs68V20ILCVriX.99