Factual error: The volcanic ash that can be seen throughout the film is too big to be real. The ash shown is something like 1-2 cm in diameter. Volcanic ash is not that big in real life; it is not more than 2 millimetres in diameter. (01:02:30)
Suggested correction: There are different types of products from volcanic eruptions: Ash, lapilli, and bombs. Ash is what everybody knows as. Lapilli is about the size of pebbles. Bombs, as shown in the movie, are large rocks on fire that can explode as they did in the movie.
Suggested correction: This in the middle of a city, where various things were catching fire, so that ash might not be exclusively from the volcano, but from burning buildings and objects nearby.
Factual error: When the wall is built and they are waiting for the choppers, we see the different news people. There is one firefighter leaning on top of the wall. The lava would be way too hot for anyone to be so close. (01:12:20)
Factual error: In the scene during the evacuation of the Cedar Hospital, Dr Calder is assessing a patient and uses the defibrillator on him. She puts the paddles in the wrong spots on the chest - right hand one over the abdomen and the other over the left lower chest. As a doctor she should know to put the right hand paddle over the upper right chest. This is important for the normal electrical pathway through the heart to reset and restart normal cardiac activity. (01:27:22)
Factual error: The volcanic lava in this movie moves incredibly fast in the subway line. This is not only inaccurate, but also ridiculous and unnecessary. Volcanic lava can possibly move faster when in a concealed area that insulates it, but insulated lava cannot move that fast.
Factual error: At the end of the movie, when it's raining, with all of the smoke and ash in the air, the rain would have likely been very acidic. The people probably wouldn't be enjoying the sudden downpour.
Factual error: The entire time the volcano is shown erupting, the volcanic lava is instantly melting everything it touches despite the fact that in real life volcanic lava would not have any human being melting because lava is more dense than water. Also lava in real life cannot instantly melt things. And no object should be sinking if caught in a lava flow.
Factual error: The firemen would have used the "jaws of life" to get the fireman out instead of the fireman jumping up on the side of the firetruck and crawling through the window. The driver was trapped and could not have been rescued without them.
Factual error: When lava engulfs the streets, aluminum light poles do not melt (it has a melting point of 1,212° Fahrenheit), yet entire vehicles with steel frames melt into the flow (steel melts at 2,750° Fahrenheit). Lava reaches around 2,000°.
Factual error: It is impossible for a volcano to form under Los Angeles. The San Andreas Fault traveling through the west coast is a "Transform" fault in which the Pacific plate and the North American plate creates a fault line that only slide past each other. In order for a volcano to form, two plates need to subduct. Because there is no ripping apart or subduction taking place along a transform fault, there isn't any magma formation to lead to volcanoes.
Factual error: Mount Wilshire is basically a shield volcano in the form of a tall stratovolcano because shield volcanoes only shoot ashes, gas, and lava (and pyroclastics for pyroclastic shield volcanoes). The lava itself behaves as if it was sentient. During the lava geyser scene, small particles of molten lava seem to be falling directly on people despite the fact that no-one was anywhere near it except for Mike, his daughter, and the little boy.
