The 'Saturday Night Live' stage at 30 Rockefeller Plaza in New York City. (Dana Edelson/NBC)Saturday Night Live is returning for Season 51 on Oct. 4, with some big changes to its cast and writing staff.The popular NBC sketch show wrapped its 50th season in May, SNL's most-watched season in three years, Variety reported. The series earned seven Emmy nominations, plus an additional 24 nominations for its specials celebrating the history of the show.The show's cast is already experiencing some shakeups ahead of the start of the new season.