The film was shot entirely in color and was intended to be released that way. It was decided during editing, however, that the movement between past and present could be made clearer by printing the Roman and Margaret scenes in black and white. Kenneth Branagh comments on the DVD that the costume and set designers were disappointed by this, because they would have used different colors for those scenes, which would photograph better in black and white, had they known this.
Robin Williams didn't want his name to appear in the opening credits as it might have misled audiences into thinking the film was a comedy. He only has 3 scenes with Kenneth Branagh and one with Emma Thompson. This was due to Robin doing 2 other movies the same year not from Paramount but from Tristar Pictures, which include Terry Gilliam's The Fisher King and Steven Spielberg's Hook.
Two additional double roles (besides Mike/Roman and Grace/Margaret) are in the film: the nun at the orphanage turns up as a snooty starlet at a party in the 1940s, and the cop at the mental hospital is seen again as an obnoxious party guest.
When we first meet Mike Church, he's parked on the wrong side of the street. Most people thought this was a nod to Kenneth Branagh's British heritage. The real reason is because Branagh wanted some Los Angeles skyscrapers visible in the background.
The scene with Grace and Mike walking along the lake at night was shot at Echo Park in Los Angeles three months after the rest of the film. It was felt that the scene was needed to show the characters growing closer together.
Mike tells Carlisle that his former patient left him 11,000 dollars in his will. He then gives Carlisle a number to call to claim 8,800 dollars, which he says is less his fee for finding him. This means that Mike's fee is twenty percent.
Kenneth Branagh, Emma Thompson, Robin Williams, and screenwriter Scott Frank have each worked with director Barry Sonnenfeld on a movie. Branagh on Wild Wild West, Thompson on Men in Black 3, Robin Williams on RV, and Scott Frank writing the movie version of Elmore Leonard's Get Shorty. Both Branagh and Thompson have worked with Will Smith on Wild Wild West and Men in Black 3 respectively.
Kenneth Branagh: [William Shakespeare)] The cover of the LIFE magazine in Mr. Madson's shop shows Laurence Olivier in Hamlet (1948); another Shakespeare reference is on the bridge where Mike and Doug fight (it reads "Shakespeare Bridge," the real name of a bridge in L.A. where the movie was filmed).
Kenneth Branagh: [uninterrupted takes] Several such scenes can be seen throughout the movie. Also, the first hypnosis scene set at the Laughing Duke features an extremely complicated camera shot in 360 degrees. It involved a great deal of precise timing and technical know-how. Although a relatively short scene, it took 15 takes and a whole day to get right.
The trivia items below may give away important plot points.
The Roman/Margaret and Mike/Grace double identities are foreshadowed by subtle similarities. *Mike who first shows up at the orphanage (former Strauss mansion) where Margaret died. Roman dies elsewhere and has to 'find' his way there, as Grace eventually does. Mike spills the cup of tea during his date with Grace, and during a flashback, Margaret spills a drink while dining with Roman. Afterwards Roman remarks that she has more "beauty than grace". These two hints foreshadow each character's past identity. *Mike's apartment contains several pictures of pianists and piano keyboards, hinting at his true identity to the careful viewer. *When Mike lays Grace down on the couch and she says this is just like Margaret and Roman, Mike says "I'm not Roman". *During "Grace"'s first hypnosis session, she throws back her head and screams, "Somebody help me!" Roman yells the same words as he holds his wife's dead body. *Grace is frequently associated with scissors. When "Doug" tries to steal her away, the prescription bottle he offers as evidence is made out to Katherine Pierce. Grace's real name is later shown to be Amanda Sharpe. *Margaret was very daring and fearless, like Mike, while Roman was more fearful and neurotic, like Grace.
During the shooting of the final brawl, in which Mike Church and Franklyn Madson are fighting, Kenneth Branagh had insisted to Derek Jacobi to make sure that he protect himself, during a moment when Madson is meant to have his head slammed into a shelf. Jacobi was meant to put his hands under his head. Unfortunately, when it came to shoot the scene, Jacobi didn't manage to and hit his head on the shelf, having a concussion for the next hour.
Casting Derek Jacobi as the stutterer Franklyn Madson made sense. Jacobi had gained fame as the Roman emperor Claudius in I, Claudius (1976). Contemporaries of the emperor made fun of his speech impediment by referring to him as "Claudius the Stammerer" and "Clau-clau-clau-claudius".