Continuity mistake: At the end it starts to rain and everyone is covered in ash, soot, dust etc. However, after only a few seconds of rain, all the ash, dust and soot have vanished off Roark, Kelly and Amy instantly. (01:32:05)
Revealing mistake: When the fire truck gets hit by a lava ball and flips over, you can see two smoke plumes coming out the bottom of the truck. These are the remains of the two cannons used to flip the truck over. (00:34:55)
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: 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.
Continuity mistake: Near the start, Roark is down in the drain and part of his mask melts. When he is back at the surface the mask is in perfect condition. (00:15:00)
Suggested correction: It was not a mask but some equipment on his chest near the radio, which looks pretty burned, when he finally gets outside.
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)
Continuity mistake: When Roark has been seen looking for a radio, there is a bloke behind Emmit who has a headset on. The camera does an instant cut to the front and the headset has gone. (00:43:40)
Continuity mistake: Just after Amy gets out of the drain, her fire suit is off her one shoulder and halfway between her shoulder and elbow. The camera cuts and it is back on her shoulder up to her neck instantly. (00:32:10)
Other mistake: Just before the lava begins to flow, the glass in a building shatters and falls on Roark and the doctor but neither suffer so much as a cut. (00:38:15)
Continuity mistake: The severity of Kelly's wound to the face constantly changes. Some shots it's extremely red and raw, others it's only slightly red. (01:22:00 - 01:22:30)
Continuity mistake: Roark's car has the windscreen smashed and cracked by the volcanic ash. In some shots, mainly a distant shot of it being driven, there are no cracks in the windscreen. (00:32:35)
Character mistake: When they're literally watching lava creep down the street Roark says "whatever this stuff is" (something like that). 2 things: 1) how does he not realise it's lava, and 2) although it's weird to have lava in LA, Amy already told him that lava could push through from the tar pits, so he should have been able to figure it out.
Suggested correction: Even if he knows what it is, he is still in denial and just doesn't want to say the name of it, as it's uncomfortable to say.
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.
Continuity mistake: When Roark reaches for the phone to call a babysitter his arm is fully stretched out, yet in the following shot its not stretched out but bent at the elbow. (00:04:30)
Continuity mistake: Between the shots when Tommy Lee Jones is talking to his ex-wife, we can see the cord from his headset changing positions from left of the boom-microphone to right and back again. (00:19:00)
Visible crew/equipment: When we see the nurse in the ER at the start, the camera passes behind a small wall and the shadow of the camera is seen. (00:04:00)
Continuity mistake: When the lava begins spilling from the tar pits, Tommy Lee's SUV is not parked next to the pits, but after the downed firetruck shot, the SUV is now there.
Continuity mistake: As the rescue crew is trying to open the disabled subway train, one man bashes the door just below the handle. A second later, he draws back to hit it again, and the door is undamaged from the first blow.
Continuity mistake: After losing her partner, Amy is above ground, taking off the equipment. As she does, her jacket goes from wide open and half off to almost closed in a second.
Other mistake: When they are trying to find a way to stop the lava from going in to the museum, Tommy Lee Jones has an idea to push a bus up against the museum to divert the lava. The plan works but the lava does not melt the bus like it melted Tommy Lee Jones' car or the fire truck.
