Mrs. Neugast lets Laurie know that she knows that her birthday is December 10th. This is Susan Dey's actual birthday.
When Mrs. Neugast catches Keith looking at a girlie magazine, the cover of the mag is a made up prop but the centerfold Keith is looking at and that viewers catch a glimpse of is an actual Playboy centerfold from October 1970 featuring twins Mary and Madeleine Collinson.