Factual error: Druig leads several warriors outside Tenochtitlan as it was sacked by the Spanish conquistadores, and they live peacefully in the nearby forest, for 500 years. The forest is of course the virgin Amazon forest, as captions say. Small problem; Tenochtitlan was in Central Mexico.
Factual error: In the scene with Sersi creating water for the crops in Babylonia, it shows corn growing. Corn was only grown in the Americas, originating in Mesoamerica. They should have shown barley, wheat, or something else growing. (00:27:45)
Factual error: There is a billboard in London advertising a display of "artifacts" at the Natural History Museum. British English spells it "artefacts" and the Natural History Museum in London only holds exhibits on natural history. A display of artefacts would be at the British Museum, a completely different institution in a different part of London. (00:07:25)
Continuity mistake: When Gilgamesh hammers the Deviant into the gates of Babylon, dealing the last strike after the dramatic pose, the shadows cast by the statues don't go much further away than their pedestal. In the following long shot the 5 Eternals have a massive area of shade behind them that extends very far away from the city walls. (00:21:30)
Factual error: The scenes set in Babylon in 575 BCE have the characters speaking Standardized Arabic to one another. At the time in Babylon, however, Aramaic language was actually spoken - Arabic as a language isn't considered by historians to have emerged until the 1st century CE. There's still Aramaic spoken in some regions of Iraq and Turkey, so it's not like the filmmakers have to use Arabic instead.
Factual error: The police car that shows up after the fight with the Deviant in London has a siren that sounds nothing like a British police siren. More like a Continental European one.
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.
Continuity mistake: When Sersi gives Dane Whitman the ring in the club, her hand goes on/off his shoulder repeatedly. (00:12:00)
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.
Continuity mistake: Sersi falls into the pool with the deviant and the pool is extremely deep, but when she turns the deviant into a tree and gets out, the pool seems shallow enough to stand in. (01:18:39)
Continuity mistake: When Ikaris flubs his line in the ancient language and Sersi and he share a moment, the hair moves on/off Gemma Chan's shoulder abruptly between shots. (00:29:00)
Plot hole: Deviants were created to get rid of dangerous local predators allowing intelligent life to thrive on the planets Arishem 'seeded'. He then created the Eternals to get rid of the Deviants once he realised they eat the species they should have protected. Problem is, it is stated that the Eternals go through their extermination routine multiple times. But the 'mistake' can't be happening all over again in a cycle, and Deviants would ruin a planet if left unattended.
Suggested correction: Arisham made them both part of the cycle to get the planet to be filled with intelligent life. So he always introduces Deviants before Eternals. It's a good way for him to tell the Eternals they are there to protect the intelligent life against the Deviants without knowing their true purpose. To keep them busy.
He refers to the introduction of Eternals as something he did "to correct my mistake." By that definition, he keeps making the same mistake over and over. If he just told them that they have to protect humanity and help their progress, he would obtain the same purpose. After all, for 500 years without Deviants the Eternals stayed put and passive as instructed and didn't create any particular trouble -if they did, they are a limited number he can easily pluck them out of the planet much more easily than a non-specified amount of ever-evolving beasts that he admits are out of his control and can grow much more powerful if they manage to kill Eternals.
He is lying. They are not a mistake, and they are not beyond his control. That's one of the main reasons why they go against Arishem in the first place, because everything is a lie, even after learning their true purpose. The Deviants are there to give the Eternals purpose, helping the intelligent life on the planet flourish, in the most natural way, for reasons we can only guess. The Deviant is upset too, learning the truth that they are only put on the planet for the Eternals to kill.
Factual error: It can be argued that the MCU is not quite our world, but certainly mirrors it closely - after all, the movie makes a point to feature real life dates and events such as Hiroshima, showing that even Cap America's actions in Europe didn't alter the outcome of WW2. It's then quite puzzling to see then Sersi gifting the savages in Mesopotamia a golden dagger that reproduces with precision one of the golden daggers in the tombs from Ur; they were Mesopotamian artefacts, sure, but from around 2600 BC and the scene takes place in 5000 BC.
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.
Revealing mistake: When inside the Forge Arishem says "I created the deviants, Sersi", you can spot Gemma Chan's beauty mark changing side - the shot is flipped. (01:01:15)
Continuity mistake: When Dane and Sersi hug towards the end of the movie, depending on the camera angle she has her right arm above his shoulder or not. (02:20:50)
Continuity mistake: On the beach for the ending, Phastus asks Sersi "How, how did you do it?" Her hair is mostly clean off the shoulder, but in the next shot she has a mess of hair all over that shoulder which goes away again when it cuts back to the previous camera angle. (02:14:00)
Continuity mistake: When the Deviant has Thena in his grasp, he caresses her. As he says "Remember", her hair is in front of the left shoulder, and it was all the way back behind the shoulder in the previous shot. (02:05:50)
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.