Throughout the series, stock aerial footage of San Francisco is used. The footage often contains the Embarcadero Freeway (I-480/CA-480) a structure that used to run along the San Francisco Bay north of the Bay Bridge. The structure was removed in 1991, a full seven years before the series started.
In several episodes (mostly from season 5 onward), you can see ceiling segments missing from the manor when low angle shots are used. The ceiling panels are in large square, sometimes rectangular segments that are able to be removed to position studio lights for certain shoots. In many scenes these are missing, revealing the open studio space above the set.