Rasche's real-life wife was chosen to play Hammer's ex-wife because they were looking for someone to play his ex-wife as someone who would stand up to Hammer and not be afraid of him. Because she was his wife and wasn't star-struck as some actresses might be, she was what Spencer was looking for.
Hammer's ex-wife's name, Susan Hilton, is a reference to Get Smart (1965). In one episode, Agent 99 claimed that as her real name. "Get Smart" producer Leonard Stern served as consultant on this series.