The skating rink is called Semoran Skateway, in Casselberry, Florida. Fun World, where Selby and Aileen ride the ferris wheel, is in Orlando, Florida on the tourist strip, International Drive.
Aileen Wuornos, a notoriously uncooperative person, gave director Patty Jenkins access to hundreds of letters she had written and received in order to gain insight into Aileen's life.
Patty Jenkins has said that she knew Charlize Theron was perfect for the role of Aileen Wuornos when she awoke to a scene of The Devil's Advocate (1997) on television. Jenkins at the time was writing her film Monster. She said that an actress that would allow a closeup of her nose running, as Theron did, would be open enough to pull off the challenging role of Wuornos.
The word "fuck" and all permutations of it are spoken 189 times.
According to Patty Jenkins, the movie was shot in 28 days, sometimes with as many as four scenes, or nine pages of script, being shot in one single day.
Patty Jenkins wrote the screenplay in only 7 weeks, while the production itself only took 2 months to be set up.
The biker bar scenes were filmed at "the Last Resort" - a bar frequented by the real life Aileen Wuornos, and the site where she was actually arrested. The bar owner (who capitalized on Wuornos' infamy by hanging a sign out in front of the bar advertising "cool beer and Killer Women") makes a cameo as the bartender who threatens to cut off Wuornos for being over her tab limit.
Kate Hudson was originally offered the role of Selby but turned the role down.