Other mistake: The first time Rachel brings the team coffee, she has six coffees on a tray. There's five cappuccinos and one regular coffee for Harry. On the tray there is five coffees on one side and one coffee at the other side, obviously being Harry's regular coffee, so that Rachel would be able to tell the them apart. But when she gives Harry a coffee, she gives him one of the five standing together, so he obviously got one of the cappuccinos.
Factual error: That truck they're driving had better be fitted with a couple of powerful rocket motors, because they outdrive a pyroclastic explosion, which would be moving at about 300kmh, and the wide shots show it's moving much faster than vehicle speed. We see the pyroclastic cloud just metres behind the truck - it would overtake them in seconds.
Suggested correction: A pyroclastic flow can have a speed of up to 400km/h. The key word here is "up to" and in reality they are usually much slower than this with the average speed being around 100km/h. Scientists believe the flow that followed the eruption of Saint Helens in 1980 had a maximum speed of just 72km/h.
Read the posting again, watch the film again. " the wide shots show it's moving much faster than vehicle speed." The pyroclastic flow at Mt St Helens may have been slow enough to outrun, but the one at Dante's Peak wasn't. This also makes this a continuity mistake as the sped of the flow varies drastically from shot to shot.
Continuity mistake: Just as Grandma jumps out of the boat you see Harry move towards her. You can see (and hear) his foot hit the bottom of the boat, when just before, it showed the boat almost completely full of acid.
Suggested correction: His pant leg to mid upper shin shows it's soaked.
Factual error: When being rescued from the crater, Harry tells the helicopter that he is 600 feet below the rim. But earlier, when first the other scientist and then Harry went down into the crater it took a very short time - that could not have been 600 feet. And also from the look of the distance it was more like 150 feet. (00:13:10)
Suggested correction: He's saying he's "about" 600ft below the helicopter, not below the rim. Also, Harry was just guessing at the distance, it could be more, it could be less.
Factual error: If the lake was already acid while the family was in the lodge for a while, the wooden docks should have already been dissolved.
Suggested correction: Different materials react with sulphur dioxide in different ways. Sulphur dioxide (or SO2) wouldn't actually dissolve wood, it would just char it and weaken it.
Suggested correction: Or the white coffee cup was for the guy that's obsessed with her coffee. Considering that it's a little bit bigger than the others and that I'm sure she wrote what each one was on the cups before handing them out, then it's very likely that the one she gave Harry was still a regular. The Grant Heskov-apologies if misspelled-also has the white cup with him, so it is possible that she gave everyone the right one.