It is established that Peggy is leaving for college shortly before Saturday the 22nd, which is consistent with the time frame of this story being September of 1934 (college began later in the 30's). However, on the day when Peggy is to leave town on the train, the calendar in Martin's office begins on a Thursday and has 31 days. September 1934 began on a Saturday and, of course, only had 30 days. (The calendar used is consistent with March 1934, which perhaps was the month in which the scene was filmed.) In any case, there is no Saturday the 22nd on Martin's calendar.
At the beginning of the film, when the delivery boy sets the package down on the desk, a clear moving shadow of the boom microphone is visible upper right of the frame.