In the morning, when Fred is going to work, his car's steering wheel is on the right side. In the afternoon, on his way home, same car's steering wheel is on the left side.
Barney disguises himself as a business tycoon to announce to Mr. Slate that he is offering Fred a better job. But as Mr. Slate is Barney's uncle, certainly Mr. Slate would have recognized his own nephew.
Jean Vander Pyl, the voice of Wilma, doubles as Slate's secretary, Miss LaRock, with a Bronx accent. Later on, as Wilma, when she tells Betty that she has been "picking up a few things for the baby," she uses Miss LaRock's accent instead of Wilma's.