When Higgins is telling Agatha an army story, she asks if it was a particular incident. Higgins replies, "No, that was Lieutenant Freebairn-Smith". This is an inside joke referring to Ian Freebairn-Smith, the composer of the original Magnum PI theme music.
Previous episodes introduced Higgins' half brothers Texan Elmo Ziller and Irish priest Paddy McGuinness, and referred to an Asian half-sister, Soo Ling. In this story the names of two other half-sisters are mentioned, native American Elizabeth Whitefeather and African Katuna Numba. This is the first story in which you can clearly see two of them in the same split screen frame.
In one scene, the framed photo by Magnum's bed is of Donald Bellisario and Deborah Pratt who were a couple in real life.
This is the second time Higgins and Father Paddy (his half-brother) are shown at the same time looking at one another. The first time was when Father Paddy McGuinness was introduced in Faith and Begorrah and Higgins met him on the rooftop of the hotel.