During the filming process, Lily James stated that she had a scene where she had to walk through an area with zombie heads all around. Of course, most of them were fake props and she was directed to stomp on one. They would have supposedly gotten squished, however she stomped and realized everyone behind cameras were all staring at her in shock. She looked down and realized she stepped on one of the few extras' head.
Several of the young cast members were inexperienced with making a comedy and would often turn to co-star Sally Phillips, who's a veteran in the field, for advice on how to improve their comic timing and delivery.
This marks Sally Phillips's second film adaptation of a book which originally was a revisited edition of Jane Austen's "Pride and Prejudice". She previously starred in Bridget Jones's Diary (2001) which source material also was a reinterpretation of Austen's classic novel.
Natalie Portman was originally cast in the film as Elizabeth Bennet before dropping out. Ironically, Keira Knightly, who is often considered her lookalike, played the role of Elizabeth Bennet in Pride and Prejudice (2005), whose original source material by Jane Austen was parodied by the 2009 novel which this film is adapted from.
The trivia items below may give away important plot points.
Lena Heady does not appear in the flesh until 34 minutes into the film in a 3 second flashback. She doesn't get a proper introduction until 58 minutes. Added up her screen time throughout the film only amounts to 6 minutes despite top billing as part of the cast.