There is some Bergman-like close photography of faces but it comes across as pretentious.  Michael Caine plays his usual bespectacled detective/spy role without any variation.

In the sauna wearing a large fur coat he claims to be hot but he doesn't sweat. Awaking among a pile of dead bodies (the people he had partied with the night before) the feeling is of the inconvenience of crawling out rather than revulsion or sorrow.

The plot concerns a computer (predictably the billion dollar brain), eggs, taking over the world etc etc etc.   The computer will be used to help spread a virus, but not a computer virus, the old fashioned human virus.

In the credits the title is also given in digits though the number is well above a billion (even above a British billion) having 18 zeroes.  The plot meanders from London to Finland and to studio Russia and studio America. But the Finnish locations are not used well and could just as well be London.  There is a rich Texan anti-communist General Midwinter ("now is the winter of our discontent") who wants to start a revolution in Latvia. He has some of the phobias of anti-Communist General Jack Ripper from Dr Strangelove (minor actor Paul Tamarin plays in both).

The army on the move look more like a group of people starting an expensive caravan holiday, and the large cast often doesn't work: the opposite of his television work- how to make a large cast seem tiny. The coup fails when Soviet planes bomb the ice and his army sinks under the water.

	Michael Caine stars.  Francoise Dorleac co-stars. Having just completed Polanski´s Cul-de-Sac she was a rising talent but sadly died shortly after Russell's film was completed. Both Cul-de-Sac and Billion Dollar Brain feature an island which is accessible by land, either when the tide is out, or over the ice.  Dorleac is the sister of Catherine Deneuve, who appeared in Polanski´s previous film Repulsion.
	The then unknown Donald Sutherland plays the computer expert. His only line is "What's going on?".  He appeared alongside Caine in Hamlet three years before.

Russell regulars Vladek Sheybal (Boyfriend, The Debussy Film etc), Alexei Jawdokimov (Isadora, The Music Lovers) and Iza Teller (Christina Rosetti in Dante´s Inferno, as well as Isadora and The Devils) have minor roles.  Stanley Caine (Michael's brother) has an appearance.  Cinematography Billy Williams, Editor Alan Osbiston.  The writer is John McGrath who also wrote Russell's Diary of a Nobody. It is based on Len Deighton´s novel. In the novel the girl is younger "she ran across the airport like a newly born antelope unsteady on its legs".  Original music is by film and classical composer Richard Rodney Bennett.  The piano is especially effective.  A Beatles song, A Hard Days Night, is also used, one of the few occasions a Beatles song has been used in a film.  Copyright restrictions and costs may have caused difficulties in re-releasing the film.

Michael Caine traps an intruder who has just picked up a packet of Corn Flakes. "Put your hands up": as he does so the cereals from the corn flake packet fall slowly to the ground.  But the scene is a bit too forced.

Caine squares up to the burly soldier who strips for a fight, but it turns out he is only stripping for a shower.

The horsemen emerging from a haze in the white snow is similar to Dr Zhivago.
Russian sailors wear their "Death in Venice" sailor costumes.
A record in Harry Palmer's room is the music of Berlioz, more the choice of Russell than Palmer. The Russian commander meets Palmer at a performance of Shostakovich's Leningrad symphony.
There are numerous train journeys including a steam train.

The computers are similar to those in Fritz Lang's Metropolis (above).
The elements play a role, with fireballs dropping from the sky, and ice turning to water.

The holocaust imagery of the dead bodies in the bath.
There is a film within the film.