Marcel Cerdan, the boxer, wasn't Édith Piaf's husband. He was her lover and the love of her life. He died in a plane crash and she never recovered from his death. She never killed anyone, let alone with a fork.
A lot of scenes and dialogue were improvised whilst shooting, with a lot of participation from the actors. The scene in which Mona draws a portrait of Tamsin on the wall of her room was entirely improvised - during Pawlikowski's traveling together with Press, he discovered that she used to do a lot of drawing while she was thinking, so he decided to integrate it into the movie and made a scene out of it.
In the book unlike the film, Mona and Phil have a sister named Lindy whom is getting married for the 2nd time. The story takes place on 23 May 1984. Mona is self-conscious of her appearance and works as a barmaid at the pub where the family lives, plays on the fruit machines and drinks alcohol to help her cope with the day. Tamsin has returned home from boarding school and seems to be lonely and Mona asked by Tamsin's father Mr. Fakenham to befriend her and Mona is off to school and decides to visit the Fakenham house only to find Tamsin's parents are arguing and due to the fact that Mr. Fakenham is having pitiful affairs.