Factual error: The opening shot is of a somewhat long and quite high bridge with an equally high waterfall behind it. After a couple views of the surroundings, Henry and Peter are standing in the middle (portion) of a stone barricade/wall (extension of the bridge?) with a huge lake behind it, waiting for the school bus. There's absolutely no legitimate or rational reason for such a location to be a school bus stop! School bus stops always have safety in mind, and this bus stop is anything but safe. (00:02:32)
Factual error: A group of people are traveling in a pickup truck escaping earthquakes and volcanic eruptions. They come across a mist that they identify as sulphur dioxide, mainly by its smell and effects on people. Then the plastic interior of the car starts to melt, and they attribute it to the sulphur dioxide. Sulphur dioxide can attack plastics and rubber, but only in its liquid form. It turns gaseous at -10° C. After that it is a gas. So the melting of plastic is not correct at ambient temperature.
Factual error: The musicians in the (real) Band of the Coldstream Guards that plays Happy Birthday for Christopher Robin are wearing their 21st-century uniforms and medals.
Factual error: When Tonya is walking through the kitchen at her job at Spud City, she complains that someone took her smokes and walks by an appliance to her left. The design style of the appliance did not exist in the early 1990s.