Just saw Kingdom of The Crystal Skull so I thought to make a thread on this.
Each film has some supernatural aspect to it. From the power of God to "interdimensional beings."
The parts in the fourth film are my favorite because they're right out of the ancient astronaut theory. The part about early Peruvians being taught farming has been mentioned as similar to a claim made by the Sumerians. The Crystal Skulls are said to have been made by aliens due to being cut against the grain from single pieces of quartz.
I loved how the Roswell Crash and Area 51 (as Hanger 51) are mentioned. Always good to see some established lore in a sci-fi film or show. Interesting take on the greys with having skeletons of quartz. In an episode of Ancient Aliens they mention quartz as a good data storage method and this could maybe explain a robotic-like acting in the Greys from abduction scenarios.