During a closeup of the Maitre D, when newlyweds Mr. and Mrs. Parkington arrive at the hotel in New York, the chambermaid with the bed warmer is seen exiting the room behind the welcoming Maitre D. In the next shot, the maid is once again leaving the room.
The gypsy fiddler plays Johann Strauss's "Roses from the South" on violin in a scene set in 1872, but that music was written in 1880.
At the beginning, when the carolers are on Mrs. Parkington's doorstep, the girl in the white coat standing on the step next to the butler is not singing "Silent Night" as the rest are. She obviously is singing something completely different.