The raft caught in the whirlpool circles continuously during the first day. On the second day, it stands still.
In the first scene, the characters walk on Huayna Picchu in 1560. American historian Hiram Bingham discovered the location in 1911. However, although North Americans and Europeans may have been unaware of it, Huayna Picchu and the nearby city of Macchu Pichu were never "lost". Locals always knew where they were, and eventually led Bingham to them. It is equally possible they could have led Spanish conquistadors there as well centuries earlier - especially if, as in the film's fictional version, none of those Spaniards lived to tell the tale.
The "dead" indigenous slave opens his eyes as the horse walks by.
The indigenous Peruvians wear clothes that were imported by Europeans in the 19th century.
The indigenous Peruvians play a song called Valicha, composed in the 20th century.
Gonzalo Pizarro died in 1548, 12 years before the film's timeline.
When the three rafts first sail along the river, two of the oarsmen on one appear to be wearing modern short trousers or 'swimming trunks' in black with a light stripe down the sides.
At about 1:22, a crew member in a white hat is visible behind Kinski when the conquistadors and Peruvians are pushing away the branches.
In one of the final shots, as the camera circles Aguirre's raft, the camera boat's wake is visible.
In one shot, when the camera moves around the rafts, the crew's quarters (a cluster of rafts with huts on them) is visible near the riverbank.
Just before the conquistador is snared in a tree, the wire that pulls him up is visible as the actor walks into the frame.
When the Spanish are coming down from the high mountains along the steep trails, near the beginning of the movie, there is a shot of a Spaniard carrying a cannon wheel on his back. In front of him, below and to the right, there is some kind of man-made structure that resembles an up-ended cart, possibly a 'hide' for the camera that films the same procession from the front..
When Pizarro sends off the expedition, he expects them to return in one week. When Don Pedro tells the men that they have to return by foot, he says that they could make it in two weeks "as Pizarro said."
All Spanish characters speak German instead of Spanish.