Joan Sims was first offered another part.
June Jago worked 10 days
Sid James spent most of his screen time in bed, as he had recently suffered a heart attack.
Contains a sly reference to Carry on Nurse, specifically the daffodil thermometer scene. When a nurse approaches Francis Bigger with a daffodil, he says, "Oh no you don't! I saw that film!"
Producer Peter Rogers had to give his wife, Betty Box, producer of the "Doctor" series of films, a percentage of the takings, for the use of the "Doctor" title.
The exterior shots of the hospital are actually of Maidenhead (in Berkshire, England) Town Hall.
The portrait hanging over one of the door is of James Robertson Justice with the caption "Dr James R. Justice, Founder". This is a reference to the rival "Doctor" series of films, produced by Peter Rogers' wife Betty E. Box, in which Justice starred.