The film was based on a then-new radio series whose first season boasted Jon Pertwee and Dennis Price among the main cast. According to Pertwee, producer Herbert Wilcox refused to hire Price for the film spin-off because Price was gay. Pertwee protested on Price's behalf, and Wilcox fired Pertwee as well.
Leslie Phillips was the only cast member from the BBC Radio series to reprise his rôle in the film. However, Richard Caldicot (the radio show's Captain Povey) makes a cameo appearance a different character.
Although the film has an almost entirely different cast, many of the character names are retained from the radio show.
The fictional HMS Trumpton was the minesweeper HMS Reedham. Also seen is the corvette HMS Portchester Castle.
Boonsey is a fictional Channel Island based loosely on Guernsey.