In Inception, Saito is supposedly a multi-billionaire who controls a big chunk of world's energy business, is able to buy entire airlines at a moment's notice and usually seen traveling in helicopters and cars with half a dozen bodyguards etc.
But in the beginning of the movie, Saito is traveling all by himself (no bodyguards or other entourage) in a public train. Why? That's a significant personal safety risk even if we ignore everything else that is off in this scene.
Is it because that scene itself was a dream (perhaps Cobb's dream in which the whole movie runs) so that the "not knowing how we got here when in a dream" thing applies? Or because he isolated himself on purpose to give Cobb a better chance of getting at him to test Cobb? Or something else?