The differences in time as judged by the narrator versus the actual time as placed by the other characters was touched upon very lightly by Ishiguro, explainable by a longer than expected nap or some such detail, but it is also made very subtly important by him as well.
After one such attempt at a nap by the narrator, he is called down to the lobby and decides to prove his point about the late hour by going down in his ‘dressing gown.’ Wherein the hotel manager hustles them out to an appointment. This is a rather common happening in dreams, where one finds oneself improperly dressed or worse, completely naked, in their surroundings. The conflicting awareness of each other would also fit in with dreamlike qualities, as well as the long dark alleyways, and the easy acceptance of the narrator of his lack of memory.
But dreams as a means of getting information into a narrative are cliche, worse if they’re used to bridge gaps or mask facts. Ishiguro isn’t doing that here though. He’s not really allowing us to think this is all a dream but rather, that life itself follows the patterns and foibles of dreams and makes it that much more interesting.