Joan Sims was second choice to play Nurse Dawson.
Bob Monkhouse was offered to play a major role but passed because he thought the fee being offered was far too low.
Wilfrid Hyde-White agreed to play the Colonel in order to return to England for the Grand National Horse race. A picture of a horse is seen on the bedside locker cupboard next to him during scenes.
John Mathews worked four weeks.
Based on the same original play as Twice Round the Daffodils
In one scene where the Colonel is seen placing bets with the medical orderly, Wilfrid Hyde-White changed the name of the horse from the scripted "Bloody Mary" to "Rambler", which Hyde-White had backed earlier in the day. Harry Locke visibly reacts to the name change, but doesn't spoil the take.
Many sources list Patrick Cargill being in this film but BFI Special Collection has all the contracts for screen performers in this, Cargill's name does not feature among those who were signed.
Producer Peter Rogers was offered a five picture deal on the strength of this film's box office success.
The "Carry On..." debut of Joan Sims. Sims became the longest serving female member of the Carry On team, appearing in 24 of the series from 1959.
The closing visual joke with the daffodil was so popular with American audiences, that plastic daffodils were given away at theatres screening the film.
When the film was released, Wilfrid Hyde-White's agent threatened to sue, on the grounds that the backside used in the daffodil gag belonged to someone other than his client. The action was dropped when it was revealed that the whole thing was done by suggestion, and that no backside is seen.