Dialog identifies the date of the hotel's $463 bill as being a Tuesday. The only year during World War II when that date was a Tuesday was 1942. Later, in a scene set a few weeks later but within the same year, Natalia mentions seeing two movies which were not released until 1943.
When Arthur throws Vivian down on the floor at the end of the film, the part of the floor she lands on can be seen to give way and spring back. It was constructed so Jane Wyman wouldn't get hurt.
Arthur reads the bill which included four permanent waves. All of the females had the same hairdos during the entire film.