Friends is still one of the most popular TV shows that was ever created, despite the show ending almost 15 years ago. Friends premiered in the early 1990s and finished airing in 2003. Many fans have found bloopers and continuity errors throughout the show over the past few years, but one of the biggest was the fact that they replaced one of the characters and hoped that no one would notice.

Carol Willick was the ex-wife of Ross Geller who realized after marrying him that she was a lesbian. The couple has a son together called Ben, who is a constant reminder of Ross’s failed marriage. When Carol made her debut on the show back in season one she was played by Anita Barone. It was only when the show producers wanted to use Carol as a recurring character that they recast the role and brought in Jane Sibbett.