Friends had a lot of celebrity cameos, some more memorable than others, but many of them represent a problem, as they don’t really make sense when looking at other episodes. Created by David Crane and Marta Kauffman, Friends debuted on NBC in 1994 and came to an end in 2004 after 10 successful seasons. The series continues to have a solid fanbase, which has grown in recent years thanks to its time on Netflix, though it’s now in streaming limbo as it waits for HBO Max, its new home, to launch.

Friends followed the lives of a group of young adults (Monica, Phoebe, Rachel, Chandler, Joey, and Ross) living in New York City and doing their best to juggle their personal, professional, and social lives while also dealing with everything adulthood threw their way. Though some topics and jokes haven’t aged well, Friends continues to be relatable to most viewers, who revisit it as many times as they can – and with these revisions, new plot holes and inconsistencies have come to light, such as the show’s celebrity paradoxes.

Related: Friends: The One Episode With Two Phoebes (In The Same Scene)

Because Friends wasn’t set in an alternate universe nor anything like that, the main characters mentioned many actors, TV shows, and movies throughout the series, which made some celebrity cameos a bit confusing.

Friends’ Biggest Celebrity Paradoxes

Friends celebrity paradoxes

Many popular actors and actresses stopped by the set of Friends for a guest appearance, such as George Clooney and Isabella Rossellini, but some arrived before or after the main characters mentioned them or watched some of their work, yet they didn’t recognize them and instead played along. One of the biggest celebrity guest stars in Friends was Bruce Willis, who played the father of Ross’ girlfriend, Elizabeth, in a couple of episodes in season 6. All is well until you remember that Joey and Chandler are big Die Hard fans, and even watch it together in season 7. Other celebrity paradoxes have their origin in season 3’s episode “The One With Frank Jr”, where Ross made his “freebie” list of famous women he was allowed to sleep with, which included Winona Ryder and Susan Sarandon – both of which appeared in season 7. Winona Ryder played Melissa Warburton, Rachel’s sorority sister in “The One With Rachel’s Big Kiss”, and Susan Sarandon played Cecilia Monroe in “The One With Joey’s New Brain” (ironically, she played an actress).

Other celebrity cameos that don’t quite match with Friends’ continuity are Elle Macpherson, who Chandler mentioned as someone he fantasized about and then appeared as Joey’s new roommate, Janine (and, funny enough, she didn’t like Chandler); Jonathan Silverman appeared in season 1 as Dr. Franzblau, and he also starred in Weekend at Bernie’s, revealed in season 4 to be Rachel’s favorite movie; Sean Penn also existed in the universe of Friends as Chandler once mentioned he broke up with a girl because she thought the capital of Cambodia was Sean Penn, and he appeared in season 8 as Ursula’s fiancé; and last but not least, Tom Selleck, who played Monica’s boyfriend Richard and starred in the series Magnum P.I, which is referenced by Ross in “The One Where No-One’s Ready”. Though these inconsistencies don’t affect the series’ overall story nor the characters' arcs, it’s funny how Friends was aware of their existence as actors, but once they showed up, everything had to change.

Next: Friends: Chandler and Rachel's First Meeting Happened Twice