According to production notes from AMPAS library files, production designer Shirley Russell was also responsible for costume design. Although Russell was not credited onscreen as costume designer, she was nominated for an Academy Award in this role.
       Prior to the opening credits, a written prologue appears: "In December 1926, the famous mystery writer, Agatha Christie, disappeared from her home for eleven days. So began a strange episode which has never been convincingly explained. There are, however, certain clues which may account for Mrs. Christie's behaviour. What follows is an imaginary solution to an authentic mystery." A written epilogue appears at the end of the story: "Two years later the Christies were divorced. Archibald Christie married Nancy Neele."
       End credits include the acknowledgment: "The producers wish to thank Harrogate Resort Services Department and Bath City Council for their assistance and also the Steamtown Railway Museum and British Railways (Eastern Region)”; and the written statement: “Filmed at Bray Studios, Windsor, England and on location in Harrogate, Bath, York and in and around London.”
       As outlined in articles in the 18 Aug 1978 DV and the 11 Oct 1978 LAT, screenwriter Kathleen Tynan, wife of British theatre critic Kenneth Tynan, became interested in the true, but unexplained, story of Agatha Christie’s eleven-day disappearance while reading articles about the author following her death in 1976. After extensively researching the topic, Tynan considered making a documentary until producer David Puttnam offered to create a feature film as a fictional account of what happened during the eleven-day period. Puttnam recruited director Michael Apted and financing was arranged through The Rank Organisation. However, Rank withdrew from the project after realizing that Christie’s first husband, “Archie Christie,” an unsympathetic figure in the story, had served on their board.
       A 19 Oct 1977 Var article announced that Dustin Hoffman and First Artists Production Company, Ltd. (FAP) acquired the project from Rank. Hoffman had signed with FAP in 1972, joining in a partnership with fellow actors Paul Newman, Sidney Poitier, Barbra Streisand and Steve McQueen. The agreement stipulated that he would trade upfront salary for artistic autonomy, star in and produce two films, and be rewarded a share of the profits and gross, as described in a 14 Jan 1975 DV article. Production costs were covered by an arrangement between FAP and Warner Bros. Pictures, who acted as distributor. Hoffman’s other film under the FAP contract was Straight Time, (1978, see entry), which was shot prior to Agatha.
       Since the contract required Hoffman to play leading roles, the small part of an English gossip columnist in Agatha was rewritten as an American journalist, starring opposite Redgrave. Consequently, Agatha’s original story about two female characters, Christie and another woman in whom she confides, transformed into a story about Christie and the newspaperman obsessed with her, as Puttnam and Tynan explained in a 23 Mar 1978 LAT article. In addition to screenwriter Arthur Hopcraft, a 21 Mar 1979 NYT article mentioned that Murray Schisgal also participated in rewrites, but he is not credited in the picture.
       Tynan indicated in an interview for the 5 Feb 1979 LAHExam that she “was not entirely happy” with the script changes, while in the 18 Aug 1978 DV article, she stated that Hoffman’s position as “outsider” in the mystery appealed to her. Script revisions remained a subject of contention throughout shooting and in lawsuits filed during post-production. An 18 Apr 1978 LAT article reported that Puttnam withdrew his name from the screen credits and was quoted as saying, “The film was irresponsibly made. Actors should never be given the sort of say he [Hoffman] had.”
       Meanwhile, Christie’s estate tried to block the production in a federal lawsuit, arguing, among other matters, that the film and novelization violated the estate’s “right of publicity.” A 28 Sep 1978 DV reported that a judge determined that the First Amendment protected the works in question as fictional writings, clearing the way for the release of the film and the novel, also written by Kathleen Tynan.
       A 9 Dec 1977 Box brief reported that principal photography commenced 7 Nov 1977 and production notes in AMPAS library files specified that location work began in Harrogate, North Yorkshire, England, the actual spa town where Agatha Christie made her getaway in 1926. Although the Swan Hydropathic Hotel, where Christie stayed, had been modernized and renamed the Old Swan, the owners allowed Shirley Russell to restore original 1920s features and furnishings. In York, England, the production used a Victorian train station, in conjunction with the historic steam locomotive, the “Flying Scotsman.” For the spa, the filmmakers shot the exterior at Harrogate’s Royal Bath House and the interior among the ancient thermal chambers in Bath, England. The city and environs of Bath were also the setting for the manhunt scenes.
       When the production wrapped, controversy continued to surround the film. A 23 Feb 1978 HR article reported that Hoffman sued FAP on 22 Feb 1978 for $66 million dollars, accusing the company of breach of contract by seizing his legal right to creative control on Agatha and Straight Time. The lawsuit also named FAP president Phil Feldman, Warner Bros., Inc. and Agatha producer Jarvis Astaire, who was Hoffman’s former manager. As alleged by the suit, FAP shut down production before completion of a final scene. According to a 21 Mar 1979 NYT interview with Hoffman, the missing scene clarified that “Wally Stanton” was a failed novelist, a motivation for his interest in Christie.
       Responding to the lawsuit’s claims in a 19 Jul 1978 Var article, FAP stated that Hoffman’s contract included a takeover clause in the event that budget and schedule exceeded certain parameters. The company declared final production costs were approximately $3.5 million, a fifteen percent overrun, and noted that the forty-nine day schedule ran an extra twenty-three days. FAP filed a countersuit against Hoffman in Oct 1978, the details of which are outlined in an 11 Oct 1978 DV article, which included complaints that Hoffman neglected post-production responsibilities, particularly dialogue looping.
       Although certain injunction requests were ruled on, the final outcome of the original Hoffman and FAP lawsuits is not known.
       In an 18 Jan 1979 LAT article, director Michael Apted stated he was “sympathetic to Dustin all along,” describing him as crucial to getting the film made. Apted also assisted in convincing Hoffman to eventually finish the necessary looping for the film’s soundtrack, as described in articles in the 24 Jan 1979 LAT and the 27 Jan 1979 NYT.
       As mentioned in production notes, Agatha marked the motion picture debut for actress Celia Gregory.