The footage of the exploding water tower comes from "The War of the Worlds"

Some of the footage of the volcano eruption comes from "When Worlds Collide"

Somehow, the idea of a nuclear war lasted 300 years really doesn't make a lot of sense.

And would such a war cause volcanic eruptions like we see in this movie?

Convenient that the Eloi all speak English.

At one point, the Time Traveller narrates that "the Morlock breed the Eloi like cattle". Yet, he seems totally surprised when he finds out how right he is (the Morlocks use the Eloi for food).

Yes, the Time Traveller helps these Eloi out. But are there other colonies of Eloi and Morlocks around the world?