Contrary to what is portrayed in the film, the real infiltrators did plan on starting the protest while the Miss World candidates were on stage. However, it was Bob Hope's misogynistic jokes that made them change their plans and start throwing their flour bombs at that very moment.
The film never mentions this, but Sally Alexander's ex-husband was the actor John Thaw. Her daughter Abi grew up to be the well-known actress Abigail Thaw, known for her role as Dorothea Frazil in Endeavour (2012).
The "Miss World 1961" mentioned so scathingly by Dolores Hope was the Welsh-born Rosemarie Frankland, whom Bob Hope described at the 1961 competition as the most beautiful girl he had ever seen. He actively tried to promote a Hollywood career for her by casting her in a supporting role in the comedy I'll Take Sweden (1965), but she proved not to have any acting ability and it was her last film. For a time, she was referred to as a "personal assistant" to Hope; it seems likely that she was, as 'Misbehaviour' implies, his mistress, although he was forty years her senior. She had two unsuccessful marriages and died in 2000, aged 57.
Released 10 days before the total lockdown in the UK due to the Covid-19 pandemic (23 March) and only 3 days before the UK government advised citizens to restrict gatherings in venues such as cinemas, severely effecting its gross box office receipts.
The movie shows Bob Hope being introduced after the semi-finalists have completed the swimsuit section. In reality he performed before that part of the contest, and the protest he provoked caused the semi-final stage to be delayed by approximately 15 minutes.