Continuity mistake: When Harry, Rachel, and the kids drive into the mine at the end of the movie, there are already tire tracks there before them, despite plenty of ash having fallen to cover tracks made earlier. Who would have been going in or out of the mine before that?
Revealing mistake: When the lava comes through Ruth's house you can see that it's done with CG. The reddish "streaks" look like from a sci-fi movie. The shapes of the lights and streaks are unnatural.
Continuity mistake: When Harry and Rachel are making their way back to Rachel's house after the volcano's initial explosion we see them go down an alley to avoid all the traffic. As they move down the alley we see a pile of bricks fall from a roof and hit the front of the truck and window which causes large cracks in the glass on the passenger side. However, immediately after this we see the car and in all shots from the outside of the vehicle the cracks are no longer visible.
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.
Continuity mistake: The watch of one of the councilmen shows 1.40. (the stubby one in the white shirt, the one that tries to get the investor to invest in the city). Some 18 seconds later it shows 1.45.
Revealing mistake: While the scientists are trying to escape, Paul and his truck get tossed aside into the swollen river, but the truck is suddenly much smaller than it should be.
Other mistake: During the end-credits, someone's title is listed as 'Mr. Bronson's Driver' instead of Brosnan.
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.
Continuity mistake: When they get in the boat to cross the lake, they notice dead fish floating on top of the water. On the other side of the lake, there are no dead fish.
Other mistake: When the lahar slams into the bridge, it seems strange that none of Paul's windows shatter while he's trying to get across. A lot of mud and debris slams into all three vehicles, but their windshields and windows remain intact. Also, the bridge entrance is washed away, but the rest of the bridge remains standing, until it tilts upward and disappears, taking Paul and his van with it.
Continuity mistake: After Terry falls in the crater, watch Harry climbing down to him. Harry is almost down, then the scene flashes to him at the top of the rim again, and he makes his way down a second time.
Revealing mistake: When Lauren screams after seeing the bodies in the hot spring, someone grabs her, but it is none of the characters in the scene.
