Helen Gregory refers to her father John as "hunyak." The term is spelled in a variety of ways and translated differently depending on the language of origin. The most common understanding is a "big lug" or unsophisticated immigrant.
Stefan Jahnchek refers to an address, 1416 N. La Brea Ave., Los Angeles, Ca. This is an actual address. It was originally the home of Charlie Chaplin Studios. Later it became the home A&M Records. It is now Jim Henson Productions.
Raymond Burr must have had a cold or illness during the filming of this episode, as his voice sounds very different than usual.
"Perry Mason" filmed some of its seasons at the former Charlie Chaplin Studios before A&M Records purchased the property. This episode probably used the 1416 N. La Brea Avenue address as an in joke, because it was one of the episodes filmed at this studio.
The correct pronunciation of the name "Jahnchek" would be 'YON-chek', not 'JON-chek' as it is used here, although that could simply be an Americanization to accommodate English-speakers. It would also most likely have been spelled 'Jahnczyk' rather than 'Jahnchek'.