Contrary to popular belief, Sir Sean Connery was not wearing a hairpiece in his first two outings as James Bond. Although he already was balding by the time this film was in production, he still had a decent amount of hair, and the filmmakers used varying techniques to make the most of what was left. By the time of Goldfinger (1964), Connery's hair was too thin, so various toupees were used for his last Bond outings.
Maurice Binder designed the gun barrel opening at the last minute, by pointing a pinhole camera through a real gun barrel. The actor in the sequence is not Sir Sean Connery, but stuntman Bob Simmons. Connery didn't film the sequence until Feuerball (1965).
This was chosen to be the inaugural movie in the James Bond film franchise as the plot of the source novel was the most straightforward. It had only one major location (Jamaica) and only one big special effects set piece.
As detailed as Dr. No's underwater lair was, one vital element was nearly forgotten: background plates of fish swimming in the sea to be added to the thick-glass window. The necessary film was quickly found among library footage the day before it was to be filmed. When it turned out the footage featured extreme closeups of fish, it was decided to have Dr. No explain that the window works as a magnifying glass.
Much is made of Ursula Andress's first appearance in the film - but in the novel, Honey Ryder emerges from the sea completely naked. When she spots Bond, she drops her shells so that one hand can cover her crotch, while the other hand hides her broken nose. This would have been impossible to depict in a big studio film at the time, due to the Hays Code censorship rules, which led to the use of Honey's iconic white bikini. Even when censorship attitudes softened somewhat over the following years, the James Bond series has generally stayed away from depictions of nudity to keep the movies accessible to broad audiences.
Bob Simmons: The series regular stuntman is the actor in the gun barrel sequence at the beginning of the movie. The same footage was used in James Bond 007 - Liebesgrüße aus Moskau (1963) and Goldfinger (1964).
Chris Blackwell: Location manager who later would found Island Records. He is also the son of Blanche Blackwell, who was neighbor, friend, and lover of Ian Fleming. He appears as the tall blond man dancing at Puss Feller's club. Blackwell later would own Fleming's Goldeneye estate, one of whose previous owners was reggae musician Bob Marley.