When waiting to see if this show would be picked up for a third season, Adam Scott left the show for the part of Ben Wyatt on Parks and Recreation (2009). Although Rob Thomas said they would have continued the show without Adam Scott, this show was ultimately cancelled.
During a 2023 interview with Ann Marie Baldonado on the National Public Radio program "Fresh Air," Lizzy Caplan recalled that she was the only actor among the group playing cater-waiters who had actually worked as a cater-waiter in her real life, albeit relatively briefly: "I did, like, a few--I've catered a few parties. I remember very vividly catering the Being John Malkovich premiere party and walking around with a tray of passed apps, none of these people, like, looking at me, like, in the eye at all--I was just like a tray that moved--and feeling those feelings that all the characters in Party Down were feeling, which was basically like, 'oh, you don't know who I am now, but you just wait. You wait!'"
Original plans for the show in the early 2000s were to feature Paul Rudd as Henry, Steve Carell as Ron, and Jane Lynch,but negotiations with networks were unsuccessful at the time. After Veronica Mars (2004) was cancelled, Creator Rob Thomas decided to bring the project back and shoot an unaired pilot at his house with a revised cast. This cast was kept when the show actually went into production, with the exception of Andrea Savage, who played Casey Klein in the unaired pilot, while Lizzy Caplan was cast when the show went into actual production. Savage guest starred on the show's second season, playing a former comedian who befriends Casey, and gives her some advice for her career.
Henry Pollard's backstory about being an actor with an obnoxious party animal character whose catchphrase was "Are we having fun yet?!" mimics Ken Marino's (Ron Donald's) real-life experience playing party animal character Louie on The State (1993), whose catchphrase was "I wanna dip my balls in it!"
Adam Scott worked on this show in season 2 with Megan Mullally, and left to work with her real-life husband, Nick Offerman, on Parks and Recreation (2009).