The Day of the Jackal (1973)

Plot hole: When the French conclude - incorrectly - that Charles Calthrop is the Jackal, they contact the British authorities and obtain his file photograph from the passport office. The photograph is of Edward Fox in character as the Jackal - but it shouldn't be! The Jackal and Calthrop have no connection. The Jackal never used his identity and did not apply for a false passport in his name. The photo should have been of Edward Hardwicke in character as Charles Calthrop, who appears in the closing minutes of the film. The two actors do not look anything like each other.

The Interrogator: You're being very foolish, Victor. You know yourself, they always talk in the end. You've seen it with your own two eyes in... where was it, Indochina? And Algeria, of course. Why don't you tell us what they're waiting for in that hotel, eh? Rodin, Montclair, Casson: what are they planning, who have they been meeting? Nobody? Not a soul, hmm? Then where were they before they went to Rome, eh? Tell us, Victor.

Trivia: The Jackal demands $500,000 (US) to assassinate De Gaulle, which seems like a modest amount for such a dangerous job. However, when you take inflation into account that's the equivalent in 2024 money of over $5m. No wonder his putative employers are surprised.

Question: Before the Jackal makes an impression of the Paris apartment key, he deliberately rubs the key against his chin. Why?