Volcano/Wall Banger

Volcano is far worse with Hollywood Science than even Armageddon can dream of, and Convection, Schmonvection is the least of it.

Only the geologist can identify the substance pouring out of the tar pits. The writers think that we don't know lava when we see it? Or that most people in LA wouldn't?
A scientist who needs a thermometer to realize that the pile of debris right next to her is over 700 degrees Fahrenheit. (For reference, that is hotter than the interior of a self-cleaning oven when it's self-cleaning.)
Our protagonist, at one point, has everyone at a certain intersection place concrete highway dividers in an arch to use the lava's own strength against it...and they set up the arch in the wrong direction. It still works.
The scene in the subway in Volcano: A man is able to move around in a train car so hot that it's melting around him. It should have been so hot that all the survivors he's rescuing would have been incinerated. Then the stupid man stupidly jumps into lava so he can throw the last survivor past it, stupidly remaining conscious and successfully throwing another grown adult clear, and then stupidly melting just like the Wicked Witch of the West. And it was stupid—did we mention that? Especially the ridiculous idea that people use the subway in Los Angeles.
The premise of the film is that, somehow, an incipient volcano could sneak up on Los Angeles, one of the most geologically monitored areas on the planet, simply because there's a subway line under construction.
There's the arbitrary way the mass of the lava is dealt with. Lava is made of stone. The massive wave of lava should have weighed many tons, but it doesn't push a bus out of its way, which a small river of water can do. Then, arbitrarily, the lava has mass again when the barricade is put up.
It snows ash throughout the film, except when it doesn't. Thanks to all that volcano ash, everyone is going to die of lung cancer soon.
- More likely Pneumonoultramicroscopicsilicovolcanokoniosis
That touching scene at the end of the film. It was parodied in South Park thus:

Chef: Hey, children, everybody! I'm back! I'm back from Aruba! What the-? [Everyone is pretty much in black-face because of the ash-storm.] Okay! Eeeeeehverybody get into line, so I can whup all your asses!

The lava seemed to speed up and slow down as was necessary to the plot.
A very small dog barks at lava slowly filling up the living room.
The noticeable lack of toxic and corrosive gases that usually accompany volcanic eruptions. There's no way that anybody would have been alive that close to the mouth of an erupting volcano.
No one seems to be aware that a volcanic eruption in the middle of Los Angeles would almost certainly result in the city being rendered unlivable for an extended period of time. Definitely months...probably years or decades.
Evacuations should have been the priority rather than trying to "fight" the volcano. The idea is suggested and bluntly rejected by our protagonist. Oh, and he heads the film's local FEMA-equivalent.

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