The sweaters worn by Beverly belonged to the real Beverly Goldberg.
Although the show is largely based on series creator Adam F. Goldberg's family, they had three sons: Adam, Barry, and Eric. ABC executives told the creators to make one of the siblings a girl because the show would be funnier. So Goldberg made the siblings Adam, Barry, and Erica.
The real life Jackie Geary (Adam's high school girlfriend) can be seen in several episodes playing her own mom.
Murray Goldberg was a doctor in real life, not the owner of a furniture store.
Most, if not all of the posters in Adam's room, were posters that the real Adam F. Goldberg had in his childhood bedroom.