Greg Rucka wrote the first draft screenplay, but when Charlize Theron came aboard, she had a number of issues with it. These were raised in a conference call with Theron, which Rucka described as "one of the worst experiences of my career". He did another rewrite but was then fired. Theron's production company commissioned a new script from new writers but Netflix hated that version. When Gina Prince-Bythewood came on board, she recommissioned Rucka, who was able to patch up his differences with Theron.
The London riverside pub that is featured in the movie is the famous Prospect of Whitby, otherwise known as the Devil's Tavern. It remains one of the oldest pubs in London, with the site dating back to 1520, making this a fitting place for the main characters to meet in London.
According to Charlize Theron and KiKi Layne, most of the stunts were performed by the actors, not stunt-doubles.
According to Charlize Theron, she received the graphic novel for the first time while shooting Atómica (2017) and after reading the first pages she felt that the story was interesting enough for a movie project.
Andy calls herself Andromache the Scythian. Scythians occupied southern parts of Eastern Europe from about the 7th century BC up until the 3rd century BC.