A Royal Charity Premiere for the film was held during February 1985 in the presence of Queen Elizabeth II and Prince Philip. The event was held at the Classic Cinema off Piccadilly and was attended by such stars of the film as Donald Sutherland, Faye Dunaway and Diana Quick. The Gala Charity Premiere Benefit was held in aid of the King George's Fund for Sailors. Reportedly, Queen Elizabeth II gave away the plot of the film when she apparently jokingly said to Dunaway, "I gather you are the one the gets killed off frightfully early--how sad".
The scene with Christopher Plummer shooting a rabbit in the woods was filmed in New Jersey and not Devon, where the rest of the film was shot. This was a scene added after principal photography had been completed--and Plummer could not return to work in England for tax reasons.
Agatha Christie's daughter, who had approval of the script, was initially concerned that Michael Elphick's police inspector, modeled to some extent after a harder-nosed American-style police officer, would prove unpopular among the local constabulary in Devon, where she lived.
Faye Dunaway's performance is seen entirely in flashback sequences and is also completely in black-and-white because all the flashbacks are in b&w. One of the film's main posters featuring thumbnail photos of the cast has Dunaway's picture, like the others, in color.
Dave Brubeck replaced Pino Donaggio as composer. The original score was not by Brubeck but by Donaggio, who wrote his typical lush and beautiful music. When the film didn't test well, the producers decided to jettison the Donaggio score and replace it with Brubeck's music. Brubeck was told he'd have two weeks to write an original score. He said no. They then agreed that they'd use already existing Brubeck tunes and newly record them. His jazzy muzak score was often negatively received by both critics and audiences.