Factual error: When Ewan McGregor drives to Belmont MA to visit Paul Emmett, he checks the mailbox to see whose mail it's addressed to. It shows the name Paul Emmett, address, Belmont MA 02324, which is the wrong zip code; it is the zipcode for Bridgewater MA, and Belmont MA should be 02478.ABernacchio
Audio problem: When the news helicopter descends on the house as the news of the ICC trial breaks on the TV, the helicopter rotor makes no sound or almost no sound until the shot changes to see it, despite it being very loud once it is visible. The sound of its blades also fades very quickly as it leaves, despite any pilot presumably being very careful so close to a building.
Trivia: McGregor finds that the BMW navigation system is active, and decides to follow the directions, having no idea where it will lead. There are obviously much easier and direct ways to check the entered target destination of a sat nav than actually following it. Instead of this being a mistake, it is most likely a script choice; portraying McGregor as stressed, technically unknowing, inexperienced driver of modern luxury cars, or all of that.
Question: Was the ghostwriter murdered? Why? The book had already been published, and he only discovered the truth about Ruth minutes before, so who would have wanted him dead?