Indiana Jones and the Infernal Machine Easter Egg - The Lost City of El Marrow

Look at the map at the beginning of the Teotihuacan level (Mexico). If you check the Yucatan Peninsula (the nobby projection south of the Gulf of Mexico) you should notice the city of El Marrow - the fictional city of the Dead where much of the Lucasarts game "Grim Fandango" takes place. Sadly, it doesn't show Rubacava or The Edge of the World. Oh well.