Back to the Future: The Massive Speaker is Meant to be the Bomb that was Dropped on Hiroshima at 8:15

Thanks to Vigil Que dropping a comment in a BTTF post about the CRM-114 amplifier 

(the CRM-114 is the nomenclature of the Strategic Air Command encryption/decryption device aboard the B-52 Stratofortress in the 1964 film Dr. Strangelove) 

I've worked out what the filmmakers of BTTF were getting at in the opening to Back to the Future with the clocks and the amplifier ... although this may be old news, but I haven't heard about it anywhere before. 

The opening scene is an analogy of the Hiroshima bomb blast, with the big speaker representing the bomb blasting Marty away just after 8:15.

 

The massive speaker is meant to be the bomb that was dropped on Hiroshima at 8:15 (the clocks are all 25 minutes slow, as we find out when Marty is late for school), which is why Marty is blown across the room, simulating an atomic explosion, because it would be too late when he flies across the room, the bomb would have detonated by the time he got there.

A watch found at Ground Zero,
Hiroshima.

These clocks are running 25 minutes slow, remember?

Hence, we see the boiling water on the hot-plate and the burnt toast when Einstein's automatic dog food machine goes off.

Burnt toast, or burnt victims of the bomb?

 "In 1938, three chemists working in a laboratory in Berlin made a discovery that would alter the course of history: they split the uranium atom. 
The energy released when this splitting, or fission, occurs is tremendous--
enough to power a bomb. 
But before such a weapon could be built, numerous technical problems had to be overcome.
When Einstein learned that the Germans might succeed in solving these problems, he wrote to President Franklin Roosevelt with his concerns. 
Einstein's 1939 letter helped initiate the U.S. effort to build an atomic bomb, but work proceeded slowly at first. 
Two other findings in 1940 and 1941 demonstrated conclusively that the bomb was feasible and made building the bomb a top priority for the United States: 
the determination of the "critical mass" of uranium needed and the confirmation that plutonium could undergo fission and be used in a bomb. 
 In December 1941, the government launched the Manhattan Project, the scientific and military undertaking to develop the bomb.
In August 1939, Einstein wrote to U.S. President Franklin Roosevelt to warn him that the Nazis were working on a new and powerful weapon: an atomic bomb. 
Fellow physicist Leo Szilard urged Einstein to send the letter and helped him draft it.
 In July 1940, the U.S. Army Intelligence office denied Einstein the security clearance needed to work on the Manhattan Project. 
The hundreds of scientists on the project were forbidden from consulting with Einstein, because the left-leaning political activist was deemed a potential security risk.
August 6, 1945 (8/6?!)
To 86 something is a slang term for killing something.
First atomic bomb dropped on Hiroshima, Japan
"Woe is me."—
Albert Einstein, upon hearing the news of the Hiroshima bombing.
On August 9, 1945, the United States dropped an atomic bomb on the city of Nagasaki, Japan, three days after bombing Hiroshima.
 By the end of 1945, an estimated 200,000 people had died in the two cities."
In other words the opening scene is an analogy of the 

Hiroshima bomb blast.
"It's 8:15 that's the time that it's always been", as OMD sing in their song about Enola Gay, the plane that dropped the bomb on Hiroshima.

The Enola Gay dropped the "Little Boy" atomic bomb on Hiroshima, which is probably why we see the movie

The Atomic Kid (Little Boy?) playing at the cinema in Marty's trip back to 1955.

The Enola Gay dropped the "Little Boy"
atomic bomb on Hiroshima at 8:15

Marty also passes this telling "broken(?)" clock that's under the bench, and what is the time on it?

?!

"Project NIKE, (Greek: Νίκη, "Victory", pronounced [nǐːkɛː]), was a U.S. Army project, proposed in May 1945 by Bell Laboratories, to develop a line-of-sight anti-aircraft missile system. 
The project delivered the United States' first operational anti-aircraft missile system, the Nike Ajax, in 1953. 
A great number of the technologies and rocket systems used for developing the Nike Ajax were re-used for a number of functions, many of which were given the "Nike" name 
(after Nike, the goddess of victory from Greek mythology). 
The missile's first-stage solid rocket booster became the basis for many types of rocket including the Nike Hercules missile and NASA's Nike Smoke rocket, used for upper-atmosphere research."
Project Nike

Einstein and the Nuclear Age
Although he never worked directly on the atomic bomb, Einstein is often incorrectly associated with the advent of nuclear weapons. 
His famous equation E=mc2 explains the energy released in an atomic bomb but doesn't explain how to build one. 
He repeatedly reminded people,  
"I do not consider myself the father of the release of atomic energy. 
My part in it was quite indirect."  
Nevertheless, Einstein was frequently asked to explain his role—as he was when a Japanese magazine editor asked him, "Why did you cooperate in the production of atomic bombs, knowing full well their...destructive power?"
Einstein's answer was always that his only act had been to write to President Roosevelt suggesting that the United States research atomic weapons before the Germans harnessed this deadly technology. 
He came to regret taking even this step. 
In an interview with Newsweek magazine, he said that "had I known that the Germans would not succeed in developing an atomic bomb, I would have done nothing.""
The Manhattan Project

Alarm/Red Balloon?

Also after Marty is blown away by the speaker, a fire bell rings, but instead of a fire alarm going off (maybe to represent Hiroshima in flames?) it turns out to be a phone ringing with the Doc on the end of the line telling Marty that the clocks are running 25 minutes slow.

"99 Luft Balloons"was a big hit in 1984 (the year before the film BTTF came out) and  
"the lyrics of the original German version tell a story: 
99 balloons are mistaken for UFOs, causing a general to send pilots to investigate. 
Finding nothing but child's balloons, the pilots decide to put on a show and shoot them down. The display of force worries the nations along the borders, and the war ministers on each side bang the drums of conflict to grab power for themselves. 
In the end, a 99-year war results from the otherwise harmless flight of balloons, causing devastation on all sides without a victor. 
At the end, the singer walks through the devastated ruins, 
and lets loose a balloon, watching it fly away."
99 Luftballons

And that the little yellow Hondo guitar he plays before he is blown away in the opening of BTTF kind of matches the colour of the stolen plutonium case his skateboard hits under the bench?

Hmm.

Not only that,but what was on the side of the plane that delivered the second atomic bomb to Nagasaki? 

Hmm.

A flying boxcar?

And when the "flying boxcar" makes its appearance in BTTF 3, Marty and his girlfriend are blown away also.

Plus, the two ties Marty is wearing in BTTF 2 when his boss on the TV yells "Mc Fry!"(?) at him, if joined together would probably go close to looking like the old Japanese flag, don't you think?