When Agent Carter takes the glove blaster from Happy, it is on her right hand then is later seen, correctly, on her left hand.
Bruce is shown taking Hope's radial pulse (in her forearm) using his thumb. As a medical doctor--among his other achievements--he should know that the correct way to take a radial pulse should be done with the index and middle finger, as the thumb has an artery in it that will make the count inaccurate.
When the train stops, they say it's because it is out of fuel. But all trains that go in/out of NYC run on electricity.
When the Wasp flies into action in the subway, Ant-Man's theme from Ant-Man. El Hombre Hormiga (2015) is heard rather than the Wasp's own theme music as heard in Ant-Man and the Wasp (2018).
In his video, Peter says that zombies are drawn to exposed human flesh. but earlier it's seen that the zombies freely attack Iron Man, even though while wearing his armor he has no exposed skin.
It's never explained how or why Iron Man, Hawkeye, and Captain America traveled cross-country from San Francisco to New York City.
The United States military should have attempt to bomb the areas infected with the zombies, BEFORE making the Avengers go in. Even if survivors got caught up in the explosions, it's still better to napalm the infected into oblivion and accept some innocent casualties over allowing an apocalypse.