Haven't seen the movie but I understand it grapically depicts human sacrifice. I believe the movie attributes the practice of cutting out the victims heart atop a Mayan pyramid by a Mayan High Priest. If I remember my history, the Mayans didn't do this, it was the Aztecs. The Mayans would occasionally throw virgins into deep limestone cisterns.
Whatever, the Aztecs used obsidian bladed knives which were not capable of cutting through the bones covering the heart so they cut from the abdomen up under the rib cage and removed the heart from the living victim and held it aloft.
When I lived in Santa Barbara, Calif. they had an "Old Spanish Days" fiesta every August. I remember one of the parade floats was a recreation of an Aztec sacrifice as part of the Mexican culture. What a weired, sick, thing to memorialize and be proud of.