(at around 5 mins) Early in the film a worry over problems in "Botswana and South Africa" is stated in the dialog, but the film is set in 1960 when the country of Botswana was still British Bechuanaland (as correctly displayed later in the film on a large map of Africa); Botswana was not renamed until its independence in 1966.
(at around 30 mins) Sir Clifton Sinclair arrives at the formal gathering at the beginning of the movie smoking a cigar. The cigar still has a band on it - it is considered extremely rude and pretentious to smoke cigars with the band still on among British society.
(at around 10 mins) When Mr. Hobbs and Ms. Quinn are first visiting in her office, she is smoking a cigarette. With each shot the length of her cigarette changes from short to long back to short and then to medium.
(at around 1h 30 mins) When Hobbs exits the utility closet he is clearly wearing two work gloves as he begins to push his cart. In the next instant, shown in the security camera, both gloves are absent as he pushes his cart.
When Laura and Mr. Hobbs originally meet in the pub to discuss the heist, there are two men playing darts only inches from Mr. Hobbs' shoulder. From the reverse angle, there is only one seated man drinking and ignoring them.
When an insurer pays a loss claim the insurer receives title to the lost item. The insured accepts the item's value in cash in place of the item, and in turn transfer title to the insurer. The insurer, effect, the "purchases" the lost item, so if the item is later recovered it belong to the insurer. Although Hobbs's goal was to ruin Sinclair, as soon as the diamonds were recovered Sinclair would have been made whole again, foiling Hobbs's intention.
When Laura tears up the note-card illustrating that there are no women managers in the company, she tears it vertically and evenly down the middle. The restored card that Mr. Hobbs shows her later has a more diagonal tear, and is made up of unequal portions.