Some of you may be familiar with the award winning film "Rail" of 1967,

https://youtu.be/guh08BGQExg

Can anyone identify the filming locations?

And I wonder what happened to all the raw source film?

Must admit I can't recall seeing that film before.

Identifying the locations could be a "fun" task, as it appears to leap about all over the place - certainly the London terminals of Paddington, Liverpool St, Waterloo, Kings Cross and St Pancras are all in the opening minute or so!
I'm sure someone must have come up with a list at some time, but can't find anything on the internet to that effect.

Will have to watch it in full at some stage.....

The British Film Institute appear to have the original films produced by BTF, though whether they have the film that ended up on the cutting room floor is another matter.
https://en.wikipedia.org/wiki/British_Transport_Films

Of the locations I can identify, this film does, indeed, lurch almost violently from location to location. This is like a constantly rotating medley of railroads around Chicago or whatnot--in on 30-second stretch I swear I saw York or Newcastle, Paddington, Southern Region, and then Ribblehead Viaduct on the Settle & Carlisle.

What I find more intriguing is an emphasis on steam a mere year or so before it was phased out completely on BR in August 1968 (or thereabouts--there were a few unofficial stragglers). This almost has the feel of a railfan movie technician making a "Farewell to Steam" art piece.

Right - I've watched all of it now.........

You can add Darlington to the stations in the start sequence - the shot that finishes with passing a North Eastern Railway water crane as it comes out of the train shed looks like that location.
The ex GWR Pannier tanks look like they are on the line out of Paddington, as they were used fairly late (1964/5?) on coaching stock workings to Old Oak Common depot. One of the GW 4-6-0's appears to be out at Old Oak on a freight train going under the North London line bridge.
The Pullman train is passing Wood Green (on the ER line out of Kings Cross) as you can read the station sign - plus several shots of the station environment (gas lamps etc) at that station feature later on.
The Southern steam (3xxxx & 7xxxx loco numbers) is on the line out of Waterloo, as that lasted until June 1967.
There are some views of Scottish (Glasgow?) style tenement housing blocks, but no obvious trains in Scotland!
Looks like the film was put together from a variety of sources, as an ex LMS Coronation 4-6-2 appears briefly at one point, and the last of those were withdrawn in 1964.

The electric stuff is all on the Euston-Liverpool/Manchester line, starting off at Bletchley, though Coventry station and Willesden Electric Depot feature as well. This electrification had only been fully inaugurated the previous year, so was the showpiece line at the time. I was even taken that way in 1966 to see what it was like on the way to see my Mothers parents near Warrington, rather than our usual cross-country train trip, so it was something of a landmark project. Best bit was, I actually was hauled by steam back from Warrington to Crewe on the return journey - my only regular standard gauge steam trip on BR! Despite only being 4 at the time, I can still remember the train pulling into the station...

Has Wood Green been closed or renamed? I can't find it.

Wood Green is in North London. (My mother lived there for a few years when she was a little girl, so the name at least is very familiar to me.)

I believe the former GNR/LNER Wood Green Station is now called "Alexandra Palace":

https://www.google.com/maps/search/alexandra+palace+station,+London,+United+Kingdom/@51.5980477,-0.1202573,15z

-Philip Marshall