Claire Wilcox (Button Blake) and David Macklin (Mike Sommers) were on a TV series at the time called Harris Against the World (1964) with Jack Klugman. The series lasted only one season.
Nearly 20 years later, Julie Adams and Ed Nelson again played a married couple at odds when they were cast members of the CBS-TV soap opera, Capitol (1982). Adams played the deceitful agoraphobic, Paula Denning, and Nelson played her husband, Senator Mark Denning. Further connection to "Perry Mason" is that Senator Denning's long-time unrequited love was Clarissa McCandless, played by five-time Perry Mason guest cast member Constance Towers.
Perry Mason drives the classic "suicide door" 1964 Lincoln Continental with tag OPD 384.
When Naomi Sutherland (Lysa D'Anjou) confronts Perry Mason and Paul Drake in the bar at the shuffleboard table, she says, referring to Dirk Blake, "I just want him cleared! That's all, cleared!" and her French accent is apparent.