After John sprays himself with milk when opening the bottle, his clothes go from covered with milk to clean from one shot to the next.
When a distraught John creates a ruckus at his office and leaves, shouting he's giving up his job, his suit is ragged and torn as he tussles with other workers. In the next scene, at home, his suit coat is perfect with no damage to it at all.
In the sequences with John and his son on the bridge over the railroad tracks, for most of the scene they are on one bridge with no overhead trusses and arched sides. Then in the last shot they are on a completely different bridge with overhead trusses and straight sides.
On the train when John is preparing for bed he leaves the men's room with a pajama top and dress slacks on under a robe, but when getting into the berth he takes off his robe and he suddenly has on the pajama bottoms.
John and Mary shouldn't be allowed to attend the company function as John very-publicly quit his job the day before.
It isn't shown or explained how Mary transports the food to the company function, nor does anyone there approach her to compliment her on the food.