Allison Janney had seriously trained to become a figure skater throughout her childhood and adolescence. However, when she was 17, she accidentally walked into a sliding glass door and gravely injured her right leg. In 2014, during an interview on "Fresh Air," Janney told interviewer Terry Gross that her leg came close to being amputated. "I lost like three-quarters of my blood. I lost an artery and cut tendon....I was in the hospital for like seven--seven, eight weeks. I missed my first year of college. You know, and after that, of course, I didn't really--I didn't skate for a very long time."
Although Margot Robbie trained extensively for the role, she was not able to perform a triple axel, nor could a skating double be found to do so, as very few women figure skaters are able to perform the jump. Producer Tom Ackerley stated, "There has been only six women since Tonya who have done a triple axel, even if there was one who was doing it today, she'd be training for the Olympics and couldn't risk doing it for the film." The jump was accomplished with the use of visual effects.
To prevent damaging her hair, Margot Robbie wore wigs as Tonya Harding. Surprisingly, the hair team used beer to achieve the "crunchy" permed look when regular hair products did not produce the desired result.
Not being a "bird" person in particular, Allison Janney had some difficulty adapting to having one perched on her shoulder for so many of her scenes. The production had to "audition" three different birds before settling on one they nicknamed "Little Man," the least hyperactive of the lot.
Writer Steven Rogers, a long-time friend of Allison Janney, wrote the role of LaVona Golden with Janney in mind. He had written several roles for Janney in the past, but other actresses ended up getting those parts. She later thanked Rogers in her acceptance speech for the Best Supporting Actress award at the 75th Golden Globes for convincing her to take the part. Janney would also go on to win the Oscar for Best Supporting Actress for her role in this film.
Nancy Kerrigan stated in interviews relating to her Dancing with the Stars (2005) appearance that she would not be seeing this movie, despite not knowing how much of it would feature her, saying, "I already lived through that."
Steven Rogers never had experience interviewing a real-life subject before the film. He initially called Tonya Harding's agent to obtain the life rights to her story and got a Motel 6. When he finally tracked her down, he found her extremely forthcoming over a two-day interview. Harding did not feel like she had anything to lose at that point.
According to Allison Janney, an effort was made by screen writer Steven Rogers to track down Tonya Harding's mother, but they had no luck. Unbeknownst to the I, Tonya (2017) production crew, LaVona Golden was being tracked down for an interview for Access Hollywood.
When Tonya Harding performed the triple axle at the 1991 Nationals, her routine was choreographed to Danny Elfman's theme for Batman (1989). Margot Robbie, who played Harding in this film, was best known to mainstream audiences for playing the iconic Batman villain and anti-hero Harley Quinn in Suicide Squad (2016).
I, Tonya (2017) is the third film Margot Robbie featured in which breaking the fourth wall is a prominent concept. The other two were The Wolf of Wall Street (2013) and The Big Short (2015). In I, Tonya (2017) and The Big Short (2015), her characters (Tonya Harding and herself) speak to the audience, whereas her character in The Wolf of Wall Street (2013) (Naomi Lapaglia) does not.