Leslie Caron states that on set there were two different meals provided for cast and crew: "bland English fare for the Brits and, for the local crew, hot, colorful, and tasty Spanish food." She preferred the latter.
Tom's car is a 1957 Ford Country Sedan station wagon (model 79C). Base price was around $2,500 --- give or take $50 depending on engine size ($27,900 in 2024). It also has the $20 optional two-tone paint job; 49,638 were made.
The aircraft flying overhead, registration F-BBUI, is a French-built Morane-Saulnier MS.502 Criquet. Built on the order of the occupying Germans during WWII, it was a copy of the more well-known German-made Fieseler Fi-156 Storch. Because of its low stall speed and short landing length requirements, it was mainly used for observation and liaison missions.
Throughout filming, the film was known as "Act Of Mercy," the title of writer Francis Clifford's novel. At the last minute, the title was changed to the meaningless Guns of Darkness (1962). The front office was worried about its box-office potential and thought the new name was more dramatic, as well as being similar to The Guns of Navarone (1961), which had been a big hit for star David Niven the previous year. It was also reported the film was re-titled for the American market.
Leslie Caron and David Niven did not get along during filming. In her 2009 autobiography 'Thank Heaven,' Caron writes: "Having nothing particularly nice to say about David Niven, I'll clam up --- only this: He had the largest hands of any partner of mine. It seems that during my young years scripts often included scenes in which I am slapped." Indeed, in closeups where the two hold hands, it is visible that Niven's hands are huge compared to hers.