The novel was published in 1930 just 12 years after the end of WWI yet Jane Marple is an old woman and treated as such by the investigating detective. This does not chime with the young Jane Marple as seen in the flashbacks scenes of her seeing her lover off to France in WWI.
Later, the Frenchman posing as one of two French magazine correspondents relates Col Protheroe's conduct in WWII, a war that didn't break out until 9 years after the novel was published.
Needless to say, the original novel is vastly different from this depiction.
I really would like to see a version with a screenplay strictly based on the original novel with a much younger Jane Marple.