Matt LeBlanc revealed in an interview that this episode's studio audience was comprised of contest winners of a tie-in advertisement campaign with Diet Coke, flown in from all over the US. He dislocated his shoulder during the scene where Joey and Chandler physically jump towards the lounge chair they fight for through the duration of the episode, and due to his injury production was shut down for the day. Subsequently the winning audience members were sent home and then once again flown in as the studio audience for another episode.
This is the only episode of the series that takes place in real time.
This is a "bottle episode", an episode with limited cast and sets produced due to limited budget. The majority of the episode takes place in the girls' apartment, (save for a quick scene during the end credits) with only the main cast appearing for most of it (except for the scene during the credits and some voices heard on the phone and answering machine).
Other than the main cast, there are only three speaking roles in this episode: Peter Dennis, who appears as Dr. Sherman Whitfield in the credits scene, and Tom Selleck and an uncredited actress who voice Richard and Michelle Burke on Monica's answering machine.
In Monica's second message to Richard, she says that maybe she's getting her period. This is a nod to Courteney Cox's commercial work before Friends (1994), when she was the first person to say "period" on national TV while appearing in a Tampax commercial.