The meso civs are well known for having Eagle units and each civ also has a unique Technology changing the stats and use in Imperial Age. That’s not the Trivia though, because every Civilization having access to rare units (eagles, elephants or lancers).
The meso civs also have a different bonus for Skirmishers (which isn’t much necessary since they and eagles both can counter archers).
Aztecs: +1 attack and range
Mayans: 0%/-10%/-20%/-30% cheaper in respective ages
Incas: no minimum range
While the Mayan one is free, the other two definitely have an edge when it comes to Genitours. The Aztecs have the best Skirmishers which maybe because their eagles are the worst when it comes to counter Arbalesters (10+ pierce attack archer units).