When all the secretaries are "working", they first change shoes from white to colored. After they make up they're hair and stuff, a man yells "coffee break!" When they all get up to go, they're still wearing their white shoes.
An exterior shot implies that nightfall is descending on New York City at the end of the workday (5pm). This would indicate that it is winter. However, most of the women employees are wearing short-sleeved or sleeveless warm-weather styles, and the CEO mentions that he plans to play golf the next day.
During opening credits number, Robert Morse and a young fellow window washer board an electric scaffolding in exterior rooftop shot, but by next scene when scaffolding has descended a few floors, co-worker is now a much older man with much less hair.
Although Finch's rise to top of corporate world is supposedly pegged to sequential chapters of same-named title book he reads throughout movie, his progress through text isn't sequential - even near end of movie he is seen poring over beginning chapters for next bit of ladder-climbing advice.
At the end of the movie, it is suggested that Finch's next career move should be President of the United States. He subsequently shows up at the White House washing the Oval Office windows. Since he had previously indicated he was 28 years old, and the movie takes place in 1967, he could not run for President until the 1976 election, as the US Constitution requires the President be at least 35 years old.