In the scene in the throne room, just after the wedding, the US Ambassador is introduced as "Cassius Clay". That is the birth name of boxer Muhammad Ali who defeated Henry Cooper, the man who played John Gully MP, the boxer. Muhammed Ali was named Cassius Clay at birth after his father who had been named after another Cassius Clay, who had been a famous Kentucky politician and anti-slavery activist in the mid-nineteenth century and was later named Ambassador to Russia by President Abraham Lincoln.
In 1970, Richard Lester had planned to make a film of "Flashman", the first of George Macdonald Fraser's novels, from a screenplay by Charles Wood and Frank Muir and with John Alderton in the title role. Because of expense, it was canceled with only days to go before the start of shooting. Half a decade later, having collaborated with Fraser on his two "Musketeers" films with huge success, Lester tried to reactivate the project, but found it easier to set up a film of Fraser's second novel, "Royal Flash", perhaps because the story is a parody of "The Prisoner Of Zenda", which had been filmed several times with great popularity. Even so, United Artists went cold on the idea shortly before filming was due to begin, but this time Lester was able successfully to transfer the project to Twentieth Century Fox. However, the film proved a critical and box-office failure, and was cut from a running time of 118 minutes to 96 minutes for general release in Britain (which accounts for certain well-known actors either not appearing or doing so only very briefly). George MacDonald Fraser so disliked the movie that he would not consent to having another one based on his Flashman novels made in his lifetime.