The voice of Sam, the receptionist who announces Rob's arrival at Drew's office, was supplied by Mary Tyler Moore. This is a reference to her role on the series 'Richard Diamond, Private Detective' as the answering service operator Sam, whose full face was never shown.
When Drew Patton first meets Laura as a guest at Rob and Laura's house for dinner, he quips, "I thought I had Miss October" (for his Emperor magazine). In the season before this one (S3), in Episode 28, the nude painting of Laura - that she had posed fully clothed for - was titled "October Eve".
The character of Lee Philips is based on Hugh Hefner, and Emperor Magazine is a parody of Playboy Magazine.