Louisa Mignone also appears in the spinoff series Ms Fisher's Modern Murder Mysteries
Two characters claim to have gone to see "an Al Jolson movie" but never mention any by name. As action of Murder & Mozzarella takes place in the later part of 1929 - and dismissing New York Nights, in which Al Jolson only had a cameo (along with Mammy's Boy (1923) which was only a film short) - the possibilities can only be, in reverse order: Say It with Songs (released in 1929), The Singing Fool (1928) or The Jazz Singer (1927).