Hart aber herzlich

The dog who portrayed Freeway, was found in an animal shelter and was named "Charlie Gray". On the set, he was especially close to Stefanie Powers. His offspring portrayed "Junior" in the later Hart to Hart movies.

Jennifer's birth year changes at least once. In the episode "Hartland Express' her birth year is shown on a driver's license to be 1946. In the episode "Harts Under Glass, her birth year is given as 1949.

Max's opening narration differs between the first season and all of the rest.

For the first season, he introduces the characters as such: "This is my boss - Jonathan Hart, a self-made millionaire. He's quite a guy. This is Mrs. H - she's gorgeous. What a terrific lady. By the way, my name is Max. I take care of them - which ain't easy; 'cause their hobby is - murder."

Beginning with Season 2 and onward, the opening lines were slightly changed: "This is my boss - Jonathan Hart, a self-made millionaire. He's quite a guy. This is Mrs. H - she's gorgeous. She's one lady who knows how to take care of herself. By the way, my name is Max. I take care of both of them - which ain't easy; 'cause when they met, it was murder."

Featured in The 33rd Annual Primetime Emmy Awards (1981)