The death of actress Diana Hyland during the production of the spring 1977 episodes forced major changes in the show. Hyland had completed only four episodes as the mother of the family and was written out of the remainder as being "away." When the series returned with new episodes that fall, Tom Bradford had become a widower, his wife having died about "a year ago."
Even though Mark Hamill didn't like the more comedic direction the show was heading in, he decided to honor his commitment to the show. However, the night the pilot aired he was involved in a serious auto accident where he sustained serious facial injuries and was forced to quit the show. Hamill has stated numerous times that the full extent of his injuries was only a broken nose.
During the first couple of seasons an instrumental version of the theme was played during the opening. However, in later seasons lyrics were added and the theme was sung by Grant Goodeve, who played David.
The kids, from oldest to youngest, were David, Mary, Joanie, Susan, Nancy, Elizabeth, Tommy and Nicholas. In real life, the actors rank thus: Joanie, Susan, Nancy, David, Mary, Elizabeth, Tommy, and Nicholas.
Aside from Dick Van Patten, for the season 3-5 opening credits, the main actors who did not appear in the pilot are billed before those who did appear in the pilot, mostly due to last name alphabetically. Betty Buckley, Grant Goodeve, Willie Aames, and Dianne Kay, who did not appear in the pilot, are billed before Connie Needham, Lani O'Grady, Adam Rich, Susan Richardson, and Laurie Walters, who did appear in the pilot.
In 1976, before Eight is Enough was even in preproduction, both Lani Grady and Betty Buckley would star in horror classics. Lani starred in Massacre at Central High and Betty Buckley starred in Carrie.
Lani Grady and Kimberly Beck, who both played Bradford sisters, both appeared naked in movies before Eight is Enough started it's first season; infact, they were both naked in the same movie together, Massacre at Central High, in 1976.
Lani Grady was the younger sister of Don Grady who played Robbie Douglas on My Three Sons, which was another popular family sitcom, like Eight is Enough was. Tragically, Lani would die of a drug overdose shortly after Eight is Enough wrapped. Robbie died too, of natural causes in 2012.