Glynis Johns and David Tomlinson later appeared together as husband and wife in Mary Poppins (1964).
Although based on the play "Miranda: A Comedy in Three Acts" by Peter Blackmore, the story closely resembles "The Sea Lady" by H.G. Wells.
The song Miranda sings at the opera is the Brindisi ("Drinking Song") from the Giuseppe Verdi opera "La Traviata".
One of the opening credits reads Tail by Dunlop. The rubber and tire company created two tails for Glynis Johns' mermaid character - one for being in the water and one for being out.
The entire main cast is noted to have all lived long lives. The titular character's actress Glynis Johns died in January 2024, three months after her 100th birthday, Googie Withers died in 2011 at the age of 94, Griffith Jones died in 2007 at the age of 97, and John McCallum died in 2010 at the age of 91. Even Margaret Rutherford was 80 at the time of her death in 1972 and David Tomlinson was 83 when he died in 2000.