These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: The Quiet Earth
Adaptation Displacement: Justified. The film was released worldwide; the book is difficult to find even in New Zealand and nearly impossible to lay hands on elsewhere.
1. Zac realized on his way back to his house that he didn't have time to get the remote control system, because the Depopulation Bomb was going to happen again too early. He took the truck in to try to save Joanne and Api.
2. Zac never intended to get the remote control, and decided to commit suicide by blowing himself up, because he still felt guilty and isolated. He thought Joanne and Api would be better off without him.