I worked nearly 37 years and retired 7 years ago from the BNSF.
I was in Maintenance Away as an electrician and never worked on the locomotives but everybody talks to each other and I know enough about some of the operation of trains
Most everyone on the internet discussing the event know nothing about train operations and what likely happened.

The Engineer rarely uses the "Breaks" in normal operation.
The trains are generally slowed by Dynamic Breaking.
There is a few feet of coupling travel between each car.
If breaks are applied incorrectly the cars will slam together and could lead to a derailment.
Yes, the Train was about 50% longer than the normal train length of about 100 cars.
I never heard about explosives being used on a derailment.
You can not travel around with explosives in the back of a truck or car without breaking dozens of Laws.

It is strange that explosives were available and used so soon after the derailment.
It was admitted that someone blew open the tank cars and set fire to the contents.
As the derailment was on such a flat area, I have doubts about the tank cars leaking.
The engineer does not operate the breaks like you do on your car and that is where people have the misconceptions about breaking.
Each car has an air cylinder reservoir that is pressurized from the air compressor on the locomotives.
Then from that air cylinder there is a mechanical linkage to the brake.
The Break is of a more metal like composition and not asbestos like on your car.
The air goes down a 2 inch air line with a rubber hose between the cars.
It takes quite some time to get the air pressure up to release the breaks.
Countless times I have heard locomotives on high idle pressurizing the trains airlines to release the breaks for travel.
Engineers and Conductors go through lengthy schooling.
They have to repeatedly qualify on simulators on proper train handling on the route they work.
Each route requires different techniques because the tracks are not uniformly flat and curves have different radiuses and slants.
A train that is 50% longer and heavier would alter the travel dynamics beyond normal train handling parameters and training.

Someone in authority had to have ordered the crew to ignore the track warning systems that check for hot bearings.
I do not understand how flames lasted so long as after the grease in the bearing burnt, there is nothing else to burn on a metal structure.
I am quite sure deliberately ignoring such warning systems is against Federal Law but you will not read about the train crew being prosecuted.

I have not read of any trainmen comment on the derailment on any forum.
I wonder why?
A trainman would be able to give firsthand account of how a train is handled.

It is late for me and wrote this as thought popped into my head.