Matthau agreed to appear on condition that Garfield rework the script to play to his own gifts as an actor. Matthau and Neame participated in the rewrites, which continued throughout the film. The AFI catalog refers to a Hollywood Reporter article describing two of Matthau's significant contributions: the ending, in which Kendig disguises himself as a Sikh in order to visit a bookshop, and the scene in a Salzburg restaurant where Kendig and Isobel, apparently strangers, strike up a conversation about wine that reveals more and more about them and ends in a passionate kiss. The original scene relied on a great deal of exposition to bring the audience up to date. Neame said that Matthau contributed so much to the final film that he could have asked for credit, but that was never pursued.