Two structural changes have been made to Mary's apartment over the summer hiatus: the window to her balcony has been replaced by double doors, and a second set of steps from the upper living area to the lower living room has been carved out of the bookcase close to the fireplace.
If you look carefully in the new show open, the clip of Phyllis and Mary is clearly an outtake. Both Mary Tyler Moore and Cloris Leachman break the fourth wall and look towards the audience laughing.
The series' second year marked the change of Mary's outfitter, from Evan Piccone, to Norman Todd, who'd remain clothier to the series' end.
In Season One, the small decorative triangles of glass in the large windows of Mary's apartment alternated between green and purple, whereas starting with this episode, they are now clear. Also in Season One, the office desks at WJM were beige, whereas starting with this episode, they are now blue.