Only When I Larf

This movie was in theaters only a few weeks after the publication of Len Deighton's novel. He had developed the subject as a novel and a movie project simultaneously, an idea that another best-selling author, Alistair MacLean, would soon take up with Where Eagles Dare (1968). Deighton was co-producer of this movie, as well as author of the novel, but is surprisingly not credited as author of the screenplay (which makes a significant change to the novel at the end of the story).

When they go to the bank the calendar by the teller says 23 October , but the check says 27-8-1968. The possible cause of this is that the check was already made out and then there was a two month delay in filming the scene.