The Misfits are looking for the tomb of a Mayan called Nahuatl. This is also the name of a language spoken by the Mayans and Aztecs, as well as a group of peoples native to southern Mexico and Central America.
When the team is driving around, searching for the tomb, Hayes is wearing a baseball cap with a "RAIDERS" logo (apparently for the NFL team, the Las Vegas Raiders). This is likely a deliberate reference to the film "Indiana Jones and the Raiders of the Lost Ark", as the plot has some similarity to the Indiana Jones movies (which the characters reference several times throughout).