Second generation actors Toby Stephens (Philip Blake) and Rachael Stirling's (Caroline Crale) respective mothers Maggie Smith and Diana Rigg starred together in another film based on an Agatha Christie novel: Evil Under the Sun (1982) which preceded this one in the chronological order of publishing.
Three of the actors who appeared in Five Little Pigs also appeared in The Murder at the Vicarage (2004), Julie Cox (Elsa Greer) played Young Miss Marple, Rachael Stirling (Caroline Crale) played Griselda Clement, and Marc Warren (Meridith Blake) played Captain Ainsworth.
Both Gemma Jones (Miss Williams) and Toby Stephens (Philip Blake) play characters in different versions of Jane Eyre: Jones as Mrs. Fairfax in Jane Eyre (1997) and Stephens as Rochester in Jane Eyre (2006).
Julie Cox (Elsa Greer) and Toby Stephens (Philip Blake) appeared together in Inspector Lewis's "A Generation of Vipers" as Miranda Thornton and David Connelly. Julie Cox is almost unrecognizable between the two shows because in Inspector Lewis, she is a plain, mousy Oxford don who doesn't wear one speck of makeup. In Poirot, she is made up very glamorously, and it's hard to tell it's the same woman.