Marianne McAndrew who plays Barry Williams' mother, is shown in a scene where "Love, American Style" is being played on TV. McAndrew guest starred on that show, as did Robert Reed and Ann B. Davis, stars of "The Brady Bunch". Both shows aired on the same night (Friday), network (ABC) and the same years (1969-1974).
Mike Lookinland, who played Bobby in the original series, plays a cameraman in the scene where Barry and Maureen keep messing up filming by kissing each other. He is the one who says, 'These two are fogging up my lens.'