This was the first and only feature film to be produced by the eminent writer Irwin Shaw (although he later produced a documentary film). Shaw had expressed loud and frequent dissatisfaction with earlier films based on his work (although the then-anonymous critic of "Time" magazine accused him of "crying into his champagne"), and decided that this screenplay, which he had adapted from two of his own short stories, would be protected if he produced the film himself, with his close friend Robert Parrish directing. The film was well-received by critics - though not the "Time" writer, who said that, if Shaw carried on like this, he would soon be "crying into his beer".
Jean Seberg played a 19 year old, but was 23, Philippe Forquet played a 21 year old, his correct age. This is relevant as the character Guy asked if she likes older men like himself.
In 1962 400 Francs = 1USD. So the hotel room was 700 Francs, i.e. 1.75USD, or about $20 in 2024 dollars. The tickets for the play were 3400 Francs, or about $8.50USD, $90 in 2024. The champagne was 3000 Francs or $7.50, $77 in 2024.
The painting that Guy takes Christina to see is "Maternity" by Pablo Picasso, 1905.