Anne Hathaway said in an interview on Good Morning America (aired on 5/7/19) that she avoided performing a traditional English accent for this film. She said that audiences know she's American and could potentially scoff at her numerous English characters. So, because her character Josephine is a con artist, Hathaway performed as if maybe Josephine is not actually English at all but speaks in an English accent as another con.
Because the film's PG-13 rating was originally an "R," Rebel Wilson had to go out and argue with the board that the film was no raunchier than similar comedies that had received PG-13 ratings featuring male actors. Her efforts prevailed.
Alex Gaumond, the actor playing the Waiter on the Train featured at the beginning of the official movie trailer, is an Olivier Award nominated actor who starred in the stage adaptation of "Dirty Rotten Scoundrels" at the Savoy Theatre, in London's West End. In the stage production, he starred opposite Robert Lindsay and played the role of Freddy Benson, which was played by Steve Martin in the original 1988 movie Dirty Rotten Scoundrels (1988), and by Rebel Wilson in this remake.
On the Stephen Colbert show Anne Hathaway revealed that her ad lib line "Well that was unexpected" was based on a time when her father was given the wrong medicine and had to sleep it off in her apartment. He slipped and fell in the bathroom and hit his head. While she was alarmed and asking if he was all right, said "Well that was unexpected."
In the scene where Penny (Rebel Wilson) first meets Josephine (Anne Hathaway) on a train heading for southern France, Josephine is reading the novel "The Curious Incident of the Dog in the Night-Time" by Mark Haddon. Alex Sharp, who co-stars in the film, made his Broadway and acting debut in the play that was the basis for that novel.
In this film, Anne Hathaway plays the analogous role to Michael Caine in Dirty Rotten Scoundrels (1988). Hathaway previously portrayed Caine's daughter in Interstellar (2014) and also acted alongside him in The Dark Knight Rises (2012).