(at around 1h 30 mins) At one point during a battle, M'Baku throws his staff to someone and jumps off a bridge into the water. The next time you see him, M'Baku is climbing into a canoe with his staff.
(at around 37 mins) When Shuri is in Riri's room near the beginning of the movie, the amount of braids Riri has over her shoulder changes every time the camera moves away and then back to her.
(at around 2h 25 mins) The position of the burial clothing on the wood-fire.
(at around 1h 55 mins) Before Shuri arrives in Jabari land with the Black Panther suit her hair is out in curls, but when she reveals herself, her hair is freshly braided. It would have taken hours for Shuri to get her hair braided, dried, and arrive to Jabari land all while M'Baku was talking.
(at around 12 mins) Near the beginning of the movie when people are diving down in submersible diving suits, there is a reading called out of "Negative One PSI". Negative pressures do not exist, and pressures less than that at sea level (between zero and one PSI) would only happen if they were going up into higher atmospheres.
(at around 1h 35 mins) A very common Hollywood misconception that a certain amount of water has to be spat out of the mouth when recovering from a drowning. The water is either in the lungs (would need to cough) or in the stomach (could vomit) but not at the back of the throat.
(at around 45 mins) When Riri is flying up to the drone, her AI states the oxygen level is at 50%, then 30%, and finally 0%. Oxygen at sea level is 21%, so 30-50% is not a problem. If the percentages given are meant to be the amount in Riri's blood, she would have been unconscious well before dropping to 50%.
(at around 1h 21 mins) When they are meeting at CIA HQ, the Naval officer sitting next to the Secretary of State has an incorrect and nonexistent rank on their sleeve. A Captain (O-6) should have only four 1/2" stripes, not five. A Rear Admiral (lower-half) would have one 2" stripe.
(at around 44 mins) Cambridge police are depicted responding in both standard sedan cruisers and SUVs. The real Cambridge police vehicle fleet is composed entirely of SUVs.
(at around 1h 10 mins) Despite Namor introducing himself with his name accented on the second syllable (and the 'a' short), nearly every time a Wakandan character references him they accent the first syllable (and turn the 'a' long). This is to satisfy the decades-old debate among fans, who have been divided between these pronunciations.
(at around 3 mins) During the funeral procession at the start of the film, several extras are clearly looking at the camera as it tracks through the crowd.
All of the clothes that the Talokan wear are bone dry even when they have presumably just emerged from the water.
(at around 1h 35 mins) Obvious green screen and CGI when Namor dives from a bridge in the capital city of Wakanda.
Throughout the movie, the subtitles use commas correctly except in one scene, where such punctuation is suddenly, starkly, noticeably missing.
In one scene, Queen Ramonda is heard speaking, but her mouth doesn't move, then the inverse: just as the scene is ending, her mouth is moving but no speech is heard.
It's never explained how Namor and his people are able to penetrate Wakanda's defenses or track Shuri to Riri Williams' location.
The Wakandans have some of the most advanced technology on the planet, and yet they choose to fight the Talokan with melee weapons rather than shooting them from afar. This is an especially puzzling decision since the Talokan seem to lack any kind of ranged weapons other than hand thrown water grenades.
(at around 1h 35 mins) The characters yell to keep Shuri back when her close relative is in respiratory arrest but she is trained as a medical and tech professional and could help rather than be a hassle.
It has already been established that Namor's powers rely on water, and yet Shuri, who is supposed to be a genius, decides to attack Namor in the ocean, rather than forcing him to fight in Wakanda, which is far from his base of power.
How was an aircraft carrier sized ship able to be moved from Wakanda, an inland kingdom, to the Atlantic Ocean?
Shuri pronounces "herb" the British way [herb], while Queen Ramonda and other characters pronounce it with the American pronunciation [erb]. This is probably due to the fact that the actress portraying Shuri, Letitia Wright, is British.
(at around 44 mins) Okoye threatens the AI by telling it its CPU won't be able to process information for "a millennia". Millennia is the plural of millennium, so "a millennia" doesn't make any sense.
(at around 40 mins) In Riri Williams' warehouse, she states that her equipment is protected by "2065 byte encryption" with an emphasis on the word "byte" as if it is some sort of algorithm or something. 2065 bytes equals 16520 bits, which would make better sense - essentially the number of digits in the code key. The actress clearly does not know what a byte is.
(at around 1h 35 mins) No attempt is made to give the drowned casualties any oxygen or even to ventilate them ("mouth to mouth").
(at around 14 mins) Near the beginning, a jellyfish in the deep sea is identified as a "phantom jellyfish." The common name is actually "giant phantom jellyfish."