The Oscar-nominated star was recreating that memorable moment when Di met with a child in Angola who had lost a leg to a land mine.
The visit occurred in 1997 during the princess's trip to the country on behalf of the Red Cross as part of an international campaign to try and eradicate the use of mines in war.
Sadly, Princess Diana died a mere seven months later
E's own Alicia Quarles caught up with the star at Target's 50th Anniversary event in New York City on Tuesday. When the duo chatted last month at the Toronto Film Festival, Watts revealed she was nervous to take on the role. So how's she feeling now?
"Not done filming and still feel that way," the actress told us. "When you're filming, you forget about it. The minute somebody starts talking to me about it I get nervous."
The movie, chronicling the last two years of her life, is scheduled to hit theaters sometime in 2013.