Other mistake: Throughout the movie, the timeframe of Ikaris and Sersi's relationship seems to constantly change; their first kiss is in 575 BC, but Phastus in 2020 asks her how could she stand him for 5000 years. Sprite tells Dane that they broke up 100 years before, but he leaves her because he can't stand to keep secret from her the mission. Which is a problem, since he mentioned that Ajak told him that when they left Babylon, so around 500 BC.
Other mistake: In 5000 BC, Eternals communicate between themselves using contemporary English. That's only expected in a movie, and they speak with natives using their own language, which some of them struggle to learn, nothing strange. Problem is, several Eternals speak English with a very noticeable accent (Scottish, Mexican, Indian) that predates any time when those cultures/nationalities existed. Lauren Ridloff's Makkari being mute speaks with ASL; American sign language, created in the early XIX century.
Other mistake: When Arishem shows his plan to Sersi, the Celestial emerging from Earth is a huge being that completely breaks the planet apart. In the movie finale, the Celestial's hand and head have popped out, but he's much smaller - thankfully, because if he truly had limbs the size of continents, the planet would have exploded before anyone could do anything about it. At that size (again, judging from lack of permanent damage from his half-birth) it's hard to imagine why his birth is supposedly doomsday.
Other mistake: The Eternal's "Domo" is in Iraq. Phastus gives a radar device to Makkari and tells her to go find the Emergence point. We see her sprint away and pass by the Cristo Redentor statue in Rio, and then end up in a spot in the Indian Ocean (she is holding the global map and we see the landmark) that is practically in the Arabian Sea. So the radar brought her literally around the world to get almost to the starting point. Later in the movie Ikaris flies up in space from that spot, and is staring down at South America.
Other mistake: Ajak uses her power to close wounds on other Eternals and when a creature heals itself everyone thinks it is Ajak's power, indicating she is the only one capable of such a feat. However, in the rest of the movie some Eternals pick up significant injuries, but even without 'the healer' are fine.
Other mistake: In the credits you can read a thank you for some of the filming that took place "at the Manoeuveres and Shooting Range of Paraja." Besides the misspelling of "manoeuvres", the shooting range is in Pajara, in the Canary islands. (02:34:00)
Other mistake: Phastus says "I always wondered how we survived the destruction of other planets that we were on." Always? That's odd phrasing; he learned the mere fact that they have been on other planets that ended up destroyed only literally a few hours before.
Other mistake: During the fight against Ikaris on the mothership, Thena is not wearing the bracelet that allows the formation of the Unimind and that she wore when she was suited up. (01:55:45)
Other mistake: Makkari looks for the Emergence using Phastos' special radar that he built. She comes back to base telling them she found the Emergence point, but does not say where it is. Despite leaving early, Ikaris is already there waiting for them; he doesn't have any problem finding it himself.
Suggested correction: It never says that the people who live with Druig in the Amazon in the present day are descendants of the people from Tenochtitlan. Nor does it ever say that the forest outside Tenochtitlan is the Amazon. He's probably been moving around for the last five centuries just as the other Eternals have.
Necrothesp
Never ever? He literally says "Do you remember this forest? Beautiful. It's the last place we all lived together. I've protected these people for 20 generations." They split after their argument during the sack of the town. If their base of operations exterminating the mutant space dogs in Mexico was in the Amazon forest, their logistic could use some work.
Sammo ★
Just because the last time they fought together was in Tenochtitlan doesn't mean that was the last time they lived together. They may have spent some time living peacefully in the Amazon before moving north to do their business in Tenochtitlan. And just because he's protected the people for twenty generations doesn't mean they're descendants of the people from Tenochtitlan. He may have found them later. We don't know every detail of the Eternals' history. You're just making assumptions.
Necrothesp
You are assuming the presence of a third party stranded for 500 years that the movie never showed before, different from the people that he led out of the city and that we have then to postulate he let go, in a location far off from the one of their last encounter. It's an assumption on entirely new details that you had to make up. My only assumption is to think that what is shown in the movie had purpose and fits, and someone just borked a caption.
Sammo ★
Who says they're stranded? He just said he had protected them for twenty generations. They'd probably always lived there. You're making the assumption that they must be the same people because nobody said they weren't. But nobody said they were either. Nobody in the film ever made a connection between the people in Tenochtitlan and the people in the Amazon. No mistake has therefore been made in either the dialogue or the captions.
Necrothesp
I noticed the same problem, the scene indicates the location as "Amazon" (it could be any of the Spanish speaking countries that have part of this forest), but then, Druig comes with the affirmation you pointed. It's obviously a geographical inaccuracy.
They don't speak Spanish in the Amazons.