The British edition of Leonard Wibberley's book has the author's original title choice, The Wrath of Grapes.

In addition to the three roles he played in The Mouse That Roared, Sellers was the model for all of the historical figures whose statues were shown around the Duchy of Grand Fenwick.

Eventually, Sellers disowned his work in The Mouse That Roared, particularly his work as the relatively normal Tully. He would later say, "I enjoyed myself more as the Grand Duchess than I did playing myself in the love scenes."

Although the opening narration states that the Duchy of Grand Fenwick is the world's smallest country, at 15 square miles it is actually larger than Monaco and the Vatican.

The Mouse That Roared has earned $50 million to date. It was filmed for $450,000, a low budget even in 1959.

The film premiered in a special screening for diplomats held in Geneva May 23, 1959.

The Mouse That Roared opened officially at the Guild Theatre in New York, where it played for two years.

Columbia Pictures sold the film with the tagline "The Hilarious Story of How the Duchy of Grand Fenwick Waged War on the U.S. -- and Won." Also used was the line "All Is Fair in Laughs and War!"

Memorable Quotes From THE MOUSE THAT ROARED

"The Americans always rush to the aid of the people they defeat....They pour money into the country of their former enemies and do anything to save the people they've beaten." -- Peter Sellers, as Prime Minister Mountjoy, explaining his plan to Peter Sellers, as Grand Duchess Gloriana XII.

"You must remember that the Americans are a very strange people. Whereas other countries rarely forgive anything, the Americans forgive everything. There isn't a more profitable undertaking for any country than to declare war on the United States and be defeated." -- Sellers as Prime Minister Mountjoy.

"We declare war on Monday, we are defeated on Tuesday, and by Friday we will be rehabilitated beyond our wildest dreams." -- Sellers as Mountjoy.

"I don't want anyone hurt." -- Sellers, as Grand Duchess Gloriana, accepting the Prime Minister's plan.

"Maybe it's a holiday." -- Sellers, as Tully Bascombe, wondering why New York City is deserted.

"Fine thing. The United States and the Grand Duchy of Fenwick are at war, and it takes the FBI to find out about it." -- Austin Willis, as the U.S. Secretary of Defense.

"How am I gonna tell the President that we've been invaded by a bunch of 15th-century Europeans." -- Willis, as the U.S. Secretary of Defense.

"Well, Your Grace, we're home. Actually, there's been a slight change of plan. I know it will come as a surprise, a pleasant one, I hope, but we sort of won." -- Sellers, as Tully, to Sellers, as Gloriana.

"I warn you, madam. I know the Geneva Convention by heart."
"Oh, how nice. You must recite it to me some evening. I play the harpsichord." -- MacDonald Parke, as General Snippet, crossing swords with Sellers, as Gloriana.

"Of course we invented the Q-bomb 20 years ago, but the working people of this great democracy are greatly interested in seeing that your Q-bomb does not fall into the hands of the capitalist war-mongering hyenas" -- Message from Soviet Union to the Duchy of Grand Fenwick.

"Ladies and gentlemen, this is not the end of the film. However, something like this might easily happen, and we thought we should put you in the proper mood. And now, back to our story." -- Narrator, after the Q-bomb seems to have gone off.

"You are a dud?" -- David Kossoff, as Dr. Alfred Kokintz, on dropping his bomb.

"The end. We Hope." -- Final title.