The “Hitch” star jetted out to the African country earlier this month to spend time with women who have suffered sexual abuse, reports dailystar.co.uk.
Mendes posted a picture from the trip on her Whosay.com page and urged fans to help raise awareness of the problems in Sierra Leone.
“I’m here in beautiful Sierra Leone, Africa. You wouldn’t believe the amount of rapes among women here, especially little girls… This is all something we need to be aware of,” she posted.
“Please help me spread the word. Much love,” she added.
Actresses Olivia Wilde, Diane Lane, America Ferrera and Nicole Kidman are also filming installments for the documentary.