When Rhoda enters Mary's apartment on the morning of Mary's first day of work, she mentions that Bess has told Rhoda that Mary's doctor friend is coming for a visit that evening. However, Mary does not receive the call from the doctor until later in the episode when she is at her desk, and she expresses surprise that he is in town.
When Mary arrives at WJM to inquire about the secretarial position, she is told the position is already filled. We never see a secretary employed in the news room in any future shows.