The inscription "Recover hope all ye who enter here" over the facility gate, is the opposite of Dante's inscription over the gate of Hell- "Abandon hope all ye who enter here".
When Jane arrives at the train station, the next train is announced as the 4:50 from Paddington. Both another famous Jane Marple mystery and the birth place of Joan Collins who has a minor role.
In the novel Carrie Louise's adopted daughter is called Pippa (though her biological daughter is Mildred in both novel and episode) . Pippa has died and her daughter's name is Gina.