Though Angela Lansbury doesn't play Jessica Fletcher, Jessica's author photo is clearly visible on the dust cover of Emma's book.
The song Emma sings "How'd you like to spoon with me?" was also performed by Angela Lansbury in the movie Till the Clouds Roll By (1946).
Jessica Fletcher never appears in person (and this is the only time in the entire series where this happens). Her lookalike cousin, Emma MacGill, proves to be a capable sleuth in her own right.
Jessica Fletcher's cousin is named Emma MacGill. In real life, Angela Lansbury's mother was named Moyna MacGill.
Although set in London, no filming takes place there.