I always liked how they framed the gun being jammed into Gregor's back at the opera, the entire scene carries a certain tension that modern films often fail to sustain or rely on things like explosions or handcannons rather than a .38 and a well acted angry whisper that you will be quietly exiting this theater or your brains will be exiting your fucking skull that is a much more accurate depiction of what it's like to operate under non-official cover.

Sadly, the movie really shows it's age when the "cultural attaché" starts lecturing Robert Redford's character that "our countries are friends now". It's hard to suspend disbelief watching it nowadays.

To swing the discussion back to cinematography:

I'm going to avoid spoilers despite it being an older movie since a disturbing amount of folks in the hacker scene have not seen it but the later scene in the tunnel, arm extended was another great cinematic... shot :-)