"The Quiet Earth" is actually based on the experience of an American tourist in New Zealand in the 1970s. New Zealanders always take the weekends off and sleep late. The tourist arrived in the center of Auckland on a Sunday morning and found it completely deserted. He later said he felt like the last man on Earth.
The book "The Quiet Earth" is a time loop novel where the action begins and ends at 6:12. In the movie, Zac Hobson grows frustrated at the lack of a response to his radio message and throws a clock at the radio. When it breaks, it displays a time of 6:12.
The scene where Zac Hobson (Bruno Lawrence) is aimlessly wandering the empty streets of the city blowing on a saxophone was an in-joke to those who knew him, as he had once stolen one when he was young, but later felt guilty and returned it.
Debut film of actor Pete Smith who played Api. Smith was a former juvenile delinquent. The Quiet Earth (1985) was not only his first acting job, it was his big break and he has been an actor ever since.
Zac Hobson (Bruno Lawrence) calls the energy grid, "Project Flashlight". Ironically enough, there was an American defense project called "Operation Flashlight" around the same time as the film. The operation, however, involved low-yield atomic blasts, small enough to destroy a single room, but nothing else.
When lying on the hood of the car, Producer Sam Pillsbury lined up all his credit cards beside him as a macabre joke. The meaning was that he was killing his personal credit by charging all the film's expenses.
The time that all clocks stopped due to 'The Effect' was 6.12 am in the morning. This is a reference 6.12 in the Bible's 'Book of Revelations'. The 'Wikipedia' website states this section can be read as: "There occurs a great earthquake where the sun becomes black as sackcloth of hair, and the moon like blood". The 'Bible Gateway' website in the New International Versions reads it as: "I watched as he opened the sixth seal. There was a great earthquake. The sun turned black like sackcloth made of goat hair, the whole moon turned blood red". The 'Early Christian Awakenings' website reads is it as: "And I saw when he opened the sixth seal, and there was a great earthquake; and the sun became black as sackcloth of hair, and the whole moon became as blood".
Another major point of comparison is the 1959 film 'The World, the Flesh, and the Devil'-- which also features a similar trio of survivors in a post-apocalyptic United States, only with the races switched. The first survivor is a black man, the second a white woman, and the third a white man. Race plays a much more explicit role in that film, whereas 'The Quiet Earth' makes statements on race more subtly.
Noted similarities between this film and the "Twilight Zone" episode "Where is Everybody?" - Both protagonists awake around 6:12 AM to find themselves alone in a small town. There is evidence that people disappeared suddenly without warning. The protagonists both break a clock. The underlying cause of the incidents turns out to be scientific experiments. The occurrences are hallucinations (this is explored more deeply in the novel "The Quiet Earth").
When Zac Hobson (Bruno Lawrence) checks in at work he hits a few buttons and the monitor starts buzzing and repeatedly displays the words, "Response....Negative." He is signaling all other stations in the worldwide grid to see if they are manned. The negative response tells him that everyone is gone in those countries, too.
Each of the survivors had a near-death experience due to a different cause. Zac Hobson (Bruno Lawrence) was a suicide, Api (Pete Smith) was a murder victim, and Joann a victim of accidental electrocution.