Newsweek reports that "although a few Mayan murals do illustrate the capture and even torture of prisoners, none depicts decapitation" as a mural in a trailer for the film does."
Temple paintings at Bonampak depicting torture and slaughter aside, anyone who has ever been to Chitzen Itza and seen the decorations in the ball court, in which a ball player is decapitated, knows that is completely wrong.
"I hate it. I despise it. I think it's despicable. It's offensive to Maya people. It's offensive to those of us who try to teach cultural sensitivity and alternative world views that might not match our own 21st century Western ones but are nonetheless valid."
Translation: this will make it harder for me to lie to my students about how horrible Westnern culture is and how sweet and innocent the pre-Colombian peoples were, views which are not based on any factual evidence whatsoever.