Pifias

The movie treats Top Secret security clearances properly at first by taking away Ian's and Louise's phones, but the rest of the staff would also be under such restrictions. There is no way that Captain Conspiracy would have had access to a laptop with WiFi, let alone be allowed to access the sites he was shown to be watching.

When Louise is first introduced to the translation team in the tent, there is a logograph on the screen of one of the computers, but they are portrayed as a new discovery when the alien first responds to her in the ship.

Colonel Weber's badges on his Army Combat Uniform (ACU) disappear and reappear. Most notably, at one point his Combat Infantryman Badge (CIB) is completely absent, but it reappears later.

When Louise and Ian enter the spacecraft the second time, it's after 2 a.m. There's the predawn light when Louise is getting ready, as seen when the spacecraft is shown, but when she exits the tent, it's still pitch black outside.

When Louise Banks and Ian Donnelly arrive by helicopter, a panoramic view of the alien landing site and human camp is shown, and then there is a stunning picture from the air. The campsite has what looks like 4 large lighting trees with shadows from the morning/afternoon sun projecting onto the ground over twice the lighting trees length. The alien ship, on the other hand, has no shadow apparent. Even though there is mist/fog on the ground below it, there should be some form of shadow visible from such a large object with the sun at that low level.

The language displayed for shots of Pakistan and Pakistani news channel are in Arabic, whereas the main and dominant literary languages used in Pakistan are Urdu and English. Arabic is spoken by barely 1% of the population and is never used in news channels.

When Louise is calling General Shang, she is using a borrowed Sat phone, while inside a tent and later inside a clean room. This is a common movie error. Sat phones only work when they have a clear view of the sky. While they may work with diminished capacity inside a canvas tent, there would be no signal inside a room.

The Russians are shown using M1 Abrams tanks, which, in reality, they do not use.

Early, when Louise is watching news on the laptop in her office, one of the news broadcasts reports that the the Bureau of Alcohol, Tobacco, and Firearms (ATF) has "put a temporary ban on new gun licenses, forcing many independent suppliers...to close their doors to the public". The ATF is a federal agency, but there is no such thing as federal firearms licensing for gun purchases as of the release of this film. The ATF issues licenses for the sale of firearms, but a ban on new licenses would have no impact on existing, licensed dealers.

When a Pakistani soldier is seen on the monitor, his uniform's color and shape are not those used by any of the forces of Pakistan. The ribbons on his left chest and the badge on his right chest do not belong to any forces of Pakistan. However, his formation sign on his upper left arm looks like one used by the Joint Staff.

Louise is told to translate some overheard Mandarin and is momentarily confused at hearing the Mandarin word for "suits" before realizing that it is a reference to Mahjong. In actual Mandarin, the word for "suit" that refers to clothing and the word for "suit" that refers to a classification of cards in a card game are not the same word. If the speakers really had been using the word "suit" in the card-game sense, Louise might have initially translated it as "flower-color" and been confused, but the only way she could have translated it initially as "suit" would be if she already knew of the card-game meaning.

However, this is not a "Factual Mistake". There is no indication that Louise ever thought of "suit" in the clothing sense. There are indeed suits (in the card-game sense) in Mahjong, but Mahjong is not a card game; it is played with tiles. In other words, Louise may have translated it as "suit" in the card-game meaning without realizing yet that the referenced game was Mahjong; and that (as well as the fact that neither card-games nor Mahjong are directly linked to the topic of the rest of the Mandarin conversation) may be where Louise's initial confusion arose from.

At the beginning, Dr. Banks says that Portuguese sounds "different from the other Romance languages". In actuality, Romanian is the Romance language that is significantly different to the others. Portuguese is quite similar to several others.

When Banks and Donnelly are arriving at the Montana site, they are shown traveling in a CH-47 Chinook, a tandem rotor helicopter. However, as they are circling for landing, the shadow of their helicopter has only one rotor. Actually, the CH-47 Chinook seen in those shots is a different helicopter landing at the base at the same time they are and seen from their point of view. The helicopter they are traveling in has one rotor.

When Louise goes to the college the day after the arrival to teach, the entire building is deserted. No students, no staff. And yet the cleaners had come in, cleaned and neatly arranged all the furniture as per usual.

It's possible the cleaners are not well-paid and felt they could not risk losing a day's wage.

When Louise has a vision of the meeting she will have with General Shang 18 months in the future, he mentions the call she made to him 18 months in the past and thanks her for what she said. At first she seems not to remember the call, and when she does, she asks General Shang what she had said to him. But the Louise 18 months in the future certainly would have remembered such a momentous call from just 18 months prior, and obviously what she said so she would not need to be reminded.

A year and a half is a long time, and when one is experiencing "non-linear time", no one can say how the memory is affected. Louise had to "travel" to the future to get the general's personal phone number, "return" to the past to make the call, then may have had multiple "time trips" before arriving at what is presumed to be 18 months in the future.

The Chinese general speaks strange Chinese with a strong Cantonese accent. This can't be real in modern Chinese military, or his colleagues and other soldiers wouldn't even understand him most of the time.

The Chinese fleet is actually just U.S. ships with Chinese flags painted on them.

When Louise called Chinese General and spoke to him in Chinese, the language she was speaking was not Mandarin or Cantonese. It cannot be understood what she was trying to say in "Mandarin".

The team ascends to the spacecraft on a platform that is elevated with a scissors mechanism. A wide shot shows the platform half-way between ground and the underside of the spacecraft, as well as how much the scissors are being unfolded at this stage. Thus, when coming close to the underside, the scissors should be even more unfolded. However, a brief shot shows they are less unfolded when the team arrives at the underside.

The Danish uniform shown on the screen of the landing site transmission from Greenland is an outdated version that only conscripts and the home guard use.

When the alarm goes off in the classroom, there is a strobe alarm on the classroom wall (for deaf people), but it does not activate. The audible alarm likely was added in post-production.

In the main landings chart, the Australian contact point seems to be in the Indian Ocean off Geralton in Western Australia. Later, there is a brief shot of an alien spacecraft with central Sydney in the distance across water; Sydney is on Australia's east coast.

A map on a TV screen shows one of the locations of the alien spacecraft landings as DEVON, UK. The spot marking the landing site is actually positioned over Wales on the screen. Devon is actually much further south.

In the main landings chart shown as (Punjab, Pakistan) landing spot is actually in Punjab, India. Punjab, Pakistan is further west of India inside Pakistan territory.

Anana Rydvald plays the Danish Scientist but is credited as Swedish Scientist.

The US alien landing site is said to be located in "Montana, just north of I-94". Interstate Highway 94 begins just east of Billings and extends to the North Dakota border and beyond. The entire area along the route is semi-arid with sparse trees and irrigated farmland along the rivers. It does not contain the lush green forests and meadows as depicted.

During a visit in the ship, the aliens' message is translated "offer weapon". Then everyone is upset about the text, and rogue military personnel even plant a bomb in the ship. It is unreasonable that Louise and Ian did not insist to clarify the precise meaning of the message during the session, rather than letting the entire Earth go mad about it.

When Colonel Weber comes by helicopter to take Louise, he said Gavisti as the answer for Sanskrit word for war. Louise said it means desire for more cows. Actually, the Sanskrit word for war is Yuddha. Gavisti means battle or desire for fighting, so it is close.

Louise uses a satellite phone indoors. Satellite phones need either a direct line of sight to the satellites or an external antenna.

Near the end, when Louise has locked herself in the clean room, calling the Chinese General on the satellite phone, Agent Harper has his gun aimed at the window and tells her she is committing treason. Treason only applies with enemies who are at war with the United States. Although this is a fictional movie, there was no mention of the U.S. being at war with China.