Sir Alec Guinness was offered the role of Lieutenant Colonel Barrow, but asked for the role of Major Sinclair instead. He then suggested Sir John Mills for the other role.
In one of the venomous exchanges between the Scots Pipe Major (Duncan Macrae) and the English Regimental Sergeant Major (Percy Herbert), the former advises the latter to go and watch his television set, adding that "Muffin the Mule (1946) is on at four o'clock". This refers to a famous British children's program of the early 1950s, which was presented by Annette Mills, the sister of Sir John Mills, who plays the Colonel of the regiment in this movie.
The torture procedure the Japanese employed on Colonel Barrow, that he describes to Captain Cairns while he was a POW, is clearly waterboarding.
As a teenager, John Fraser had been a member of a pipe band at his school, and although he played the big drum in the band and not the bagpipes, he was familiar enough with the musical instrument to be able to mime the movements required for his role in this movie.