Lead Julia Garner actually visited Anna Delvey (born Anna Delvey Sorokin) in Rikers Island prison as part of her research for the role. In the course of their conversation, Delvey asked Garner how the shoot was going and how she was going to portray her in the series. Garner found Delvey to be quite intimidating at times, even with journalist and series co-writer Jessica Pressler present in the room throughout the interview.
The role Anna Chlumsky is playing is based on the same journalist Julia Stiles portrayed three years earlier in Queens (2019)
Left unmentioned in the miniseries is the fact that Netflix and Shonda Rhimes, whose production company produced the show, optioned Jessica Pressler's article about Anna only a few months after it appeared in print - almost a year before her real-life trial. Pressler attended the trial, but only for purposes of including it in the miniseries; she had parted ways with New York Magazine by then.
Completion of the series was delayed for over a year by the coronavirus pandemic. While most of it was shot prior to the pandemic-related shutdowns that began in March 2020, it had been filmed outside of the episodes' sequential order, and the cast & crew had to reassemble in mid-2021 to finish filming. The delay can be "seen" onscreen in the backgrounds behind each exterior scene filmed on location: a single episode can bounce back and forth between scenes filmed during a frigid New York City winter to ones shot during the summertime.