Patty Terwilliger Smith (Dame Maggie Smith) takes Willard C. Gnatpole (Bob Newhart) shopping, where she is seen trying on clothes and buying an outfit for twenty pounds sterling at the Apple Boutique on Baker Street, London, a boutique owned and operated by The Beatles. The boutique, which was the first venture of their Apple Corps Ltd. company and featured a large psychedelic mural on the external wall, was only operated for several months in 1968 before being closed down, and the contents given away to the public for free. This movie provides one of the few rare filmed glimpses of the boutique's interior.
Peter Ustinov agreed to be in this film on condition that the American setting was changed to a British one, and his and Maggie Smith's characters were made British, not American (though their very American names are retained). He did extensive rewriting on the film, although he praised original author Ira Wallach.
Maggie Smith, who portrays the pregnant Patty Terwilliger Smith in this film, would give birth to a son (actor Toby Stephens) just seven months after this film's release.
The M505 is an English Electric Computers Leo 3 System 4. The manufacturer's name can be seen on the monitor.