Donald Drake (Fairbanks) and his wife Penny (Donlan) are an American couple who inherit a farm in Sussex. One day, Penny goes to town with the farmhand Reuben (Pertwee) and through a wacky misunderstanding, returns home with five dozen ducks that she cannot return. The Drake couple tries their best to adjust with looking after their new farmyard ducks but discover that a hen has laid a uranium egg, leading to the armed forces arriving to quarantine the farm. Hilarity Ensues as the Drakes try to deal with living in the same house as Reuben, their handyman Higgins (Peter Butterworth), a loan officer and an official from the Agricultural Ministry.
Often known by many as one of Douglas Jr.'s last films in his career (and one of the last he ever did in his stint in the British film industry) Mr. Drake's Duck has been compared to the American sitcom Green Acres mixed with a non-romantic Screwball Comedy.
- Accidental Bid: The auctioneer mistakes Penny's waving as a bid, which forces her to take the ducks with no refund.
- Accidentally Broke the MacGuffin: As the army try to remove the radiated egg, they operate on the duck that laid it. They picked the wrong duck and the operated one dies in surgery.
- Added Alliterative Appeal:
- Higgins the handyman.
- Donald Drake, with the onomatopoeic sounds being slightly different.
- Apology Gift: Penny writes "I'm sorry" on Donald's hard-boiled egg when he finds out about the ducks she accidentally bought. Donald writes "Me too" on Penny's egg.
- Cloudcuckoolander: Penny is definitely this. Some online reviews compare Donlan's performance to the sort of Dumb Blonde character that Marilyn Monroe would later be known for.
- Egg MacGuffin: The egg full of uranium egg yolk. The army is sent in to remove the egg and find the duck that laid it.
- Happily Married: Donald and Penny.
- Lockdown: The farm is put on lockdown by the army so that the radiation would be removed.
- MacGuffin: The duck that laid the egg is very valuable to the governments around the world so the army also tries to track down the egg's mother.
- Running Gag: The Bren carrier cannot seem to open the gate without knocking it over when he enters and leaves.
- Skewed Priorities: Donald and Penny are more annoyed that their farm is trashed than being locked in their house with their staff and strangers for over 24 hours.
- Shout-Out: A possible one with Donald Drake. A "drake" being a male duck.
- The Simple Life Is Simple: With the help of the hired help and some farming manuals, Penny and Donald manage to run their farm successfully, despite the culture clash and no other experience.
- Unexpected Inheritance: Donald, who has never done any farmwork in his life is suddenly given a farm from his uncle. In another country, no less.
- Whole Plot Reference: The movie appears to be loosely based on the fable The Goose That Laid the Golden Egg. Those who know how that story ended will see this movie having a Foregone Conclusion.