During one of the flashbacks, Edith is playing a song called The Sabre Dance on the xylophone. The flashback was supposed to be in 1934, but the song wasn't composed until the 1940's.
Isla Fisher was rumoured to play Gwenda.
Jackie Afflick: Miss Ballantyne.
Eve Ballantine: Mr. Afflick.
Jackie Afflick: How's tricks?
Eve Ballantine: Tricky.
The point of Gwenda remembering the original murder is that she is looking THROUGH the hall banister railings because she was only a child. In the flashback at the end, though, the child is seeing looking OVER the banister.
Claire Halliday (Helen Marsden) - Strangled
Kelvin Halliday - Pushed off cliff
Lily Tutt - Strangled
Sleeping Murder was filmed by the BBC in 1986 as a two-part mini-series under the series Miss Marple. It was directed by John Howard Davies and starred Joan Hickson as Miss Marple. This new adaptation (with many extreme plot changes) was filmed in 2005.
Sleeping Murder was shown in two parts in the US and aired from June 4th to June 11th.
Sleeping Murder the first episode of the second season, attracted 8.4 million viewers, 400,000 more than The Body in the Library (the first episode of the first season). This was the highest viewing audience out of the five episodes shown so far.
This episode is based on the novel by the same name published in 1976. The book itself was written during WWII, as Agatha Christie was afraid of being killed in an air raid. This and Poirot's final case Curtain were both held in a vault bank and released after her death.