Matt LeBlanc actually has done soft core porn in Red Shoe Diaries (1992), an erotic anthology series that ran on Showtime in the early '90s.
Having an extra nipple is not as uncommon as people may think. As many as 1 in 15 people may have one, which are rarely fully formed, which means they aren't very noticeable, even on women. They do tend to occur on men more often than on women.
The first episode with Phoebe's name in the title.
Jennifer Aniston (Rachel) and Steve Zahn (Duncan) would go on to appear together in The Object of My Affection (1998) and Management (2008).
Lauren Tom's (Julie) husband in real-life, Curt Kaplan has played with Matt LeBlanc (Joey) in Ed (1996) and then with David Schwimmer (Ross) in Breast Men (1997).