When Tsao is stabbed, the bloodstain moves from one side of his shirt to the other. In the first shot, it is on his left side. In the two following shots before he is stabbed again, the blood is on his right side.
In the opening scenes in Shanghai, Wong is driven in Mrs Yee's Buick, which must be a 1942 model. A "gunsight" hood ornament is clearly seen. That ornament was not used until 1948. Also, the grille of the car changes from one with bars overlapping the front bumper to one with the bars entirely enclosed. The 1942 Buick did not have bars that overlapped the bumper.
(at around 1 min) An Indian policeman wearing a red headband is seen directing traffic on the left side of the screen. When they park the car, the same Indian policeman has magically moved to the right side of the screen.
The story ends with Mr. Yee and Wong picking up the ring just after the mahjong game from the opening scene. During this game one of the ladies mentions a ring with a gemstone as large as an egg. While choosing the gem for the ring earlier in the story Wong refers to this remark which clearly takes place later on in the story.