Historical films are a staple of Hollywood, often drawing huge budgets and, more importantly, huge profits. Some films stay true to their time period and their characters, with films such as Lincoln or Agora providing exceptionally interesting stories with few real changes to the history.
Others, however, have no quandaries about changing dates, numbers, characters, and occasionally, history altogether. Whether it's confusing one person's story with that of another, or mixing up entire civilisations, Hollywood likes to play it fast and loose with what really happened.
Most of the time, directors will push these changes under the bracket of "artistic license," or try to argue that they're attempting to tell the story, not the facts. This is often because a director wants to spin a movie a particular way, ignore what really happened, or because they don't think it would make a good movie.
The problem with this is that more often than not, the facts turn out to be a far more interesting story than what audiences end up receiving. This usually results in a mix of authentic moments blended with complete fiction, leaving viewers walking away thinking everything they saw was completely true.
At least until they look it up on Wikipedia...
Using the real ancient Mayan language might give Apocalypto a feel of authenticity, but this covers up the reality of its historical roots. Documenting the fall of the Mayan kingdom, Apocalypto's makeup and the weapons used were heavily researched from images on pottery, as with Jaguar Paw's wife, Seven, who has a tattoo of the Mayan number seven on her arm. But this is a Mel Gibson film, and he isn't going to let something like "facts" or "history" stand in the way of his film.
Apocalypto received a huge backlash for its portrayal of the Mayan people as primitive savages, living in the middle of an uncleared jungle. In reality, the Mayans were extremely advanced, and understood the nature of crop cycles. Similarly, stone-built settlements were incredibly common, but Apocalypto displays them as being rare and only mentioned in stories.
One of the most controversial point of Apocalypto, however, is the portrayal of human sacrifice. While it is accepted that there was some human sacrifice in the Mayan kingdom, it wasn't to the extent displayed in Apocalypto, and it didn't involve heart extraction.
More often, the Mayans performed their sacrafices via decapitation, or used non-lethal blood-letting. Mel Gibson seemed to be confusing the Mayans with the Aztecs, and it's not the only time he did this. The end of the film shows the Spanish conquistadors beginning to land on the beach. In 900AD. Six hundred years before that actually happened. To the Aztecs.