The trigger for this eruption was an oil rig drilling into the side of the volcano, releasing a gusher. Oil fields are not found on or near active volcanoes as there is not enough time between eruptions for any petroleum products to be deposited or to form.
Gilmore says the death toll from the Mt. Pelée eruption resulted from suffocation when the volcano's explosion sucked oxygen out of the air. In actual fact the major killer was a pyroclastic flow of gas and volcanic debris that buried and almost entirely incinerated the town of Saint-Pierre.
After night falls, characters and/or the camera view the volcano from various angles - some 90 degrees removed from one another - but are always seeing the same side of the volcano with the same patterns of lava flow (since it is actually a piece of stock footage matted into the frame).
The size of the volcano and distance from the hotel when viewed from the cave seemed off and too close. The size and destructive force of the lava bombs from the volcano was exaggerated to make the viewer believe that they would destroy the entire hotel complex as though it had been nuked with one or two hits.