California Doubling: The underwater scenes are supposed to be Gibraltar, but were shot in the Bahamas; also, since Japan didn't allow for Stuff Blowing Up in a national park, parts of the Little Nellie battle were shot in Spain.
Cast the Runner-Up: Mie Hama was originally intended for the larger role of Aki, but doubts over her mastering of English, meant that she was ineligible for the part. Hama's reported depression over losing the role, and the disgrace it would bring to her family (she threatened to throw herself off the Imperial Hotel), was instrumental in her taking the equally important, though less vocal part of Kissy Suzuki. Meanwhile Akiko Wakabayashi was originally cast as Kissy.
With 007 You Only Live Twice (Brazil and Portugal)
007 Seized The Rocket Base'' (China).
The Danza: Aki is played by Akiko Wakabayashi. The character, formerly "Suki," was renamed at her request. (Mie Hama had been supposed to play this role until she was given a part that better suited her limited grasp of English.)
Executive Meddling: Producer Harry Saltzman hired Jan Werich to play Blofeld without consulting director Lewis Gilbert or fellow producer Albert Broccoli, an example of the increasingly eccentric decisions that eventually helped force him off the series.
Hostility on the Set: The atmosphere during the production was reportedly chilly. Sean Connery had grown bored with the Bond role and frustrated with the public fascination with the franchise. The posters declaring that "Sean Connery IS James Bond" didn't help. Furthermore, Bernard Lee and Lois Maxwell were appearing in the knock-off film Operation Double 007 with Neil Connery, Sean's younger brother, and the elder Connery let them know he was not happy about it. Furthermore, Connery's relationship with Broccoli and Saltzman had deteriorated to the point where he refused to act if either of them were onset.
The Other Marty: ...however, he wasn't the first person who attempted to do so. The original actor they cast was Jan Werich, who proved completely wrong for the role for looking too grandfatherly◊ (being even compared with Santa Claus) and so was replaced by Pleasence. In the final cut, many of Blofeld's scenes prior to The Reveal still feature Werich, as only his hands and legs are visible, meaning that all they needed to do was have Pleasence overdub his dialogue.
Mie Hama was having trouble learning English, while Akiko Wakabayashi had much progress. Since the former took this so seriously that she threatened to kill herself if fired (she was afraid of dishonoring her family), the producers just traded the roles between actresses, as Kissy appears much later in the story and has fewer lines.
The Toyota 2000GT wasn't supposed to be a convertible, but it got converted into one due to Sean Connery's height.
Stunt Double: Mie Hama was unable to film the scenes where she was swimming (some sources say she didn't know how to swim, some say she was ill). Sean Connery's then wife, Diane Cilento, volunteered to film the scenes, disguising herself with a black wig.
Throw It In!: While everyone else is remarkably calm, Blofeld's cat gets completely freaked out and tries to escape when the control room starts taking structural damage.
Tsai Chin, who plays the girl Bond sleeps with in the opening teaser, played one of Bond's poker adversaries in Casino Royale (2006).
Shane Rimmer plays a NASA operator. He would later play Willard Whyte's space operator in Diamonds are Forever and Commander Carter in The Spy Who Loved Me.
Ed Bishop is the Hawaii capcom as the NASA capsule encounters a mysterious spaceship in the cold open. A couple of years later, he'd encounter a lot more unidentified flying objects as Ed Straker in UFO.
This film's version of Blofeld was specifically parodied as Doctor Evil in Austin Powers, as were a few other tropes such as the hollowed out volcano lair.
Most of Syndrome's island base from The Incredibles is likewise based off of Blofeld's lair, from being a launch facility built out of a volcano, to the monorail pod-based transit system. Even some shots were directly recreated, such as the slow revolving shot from a tram of a hero seeing the launch vehicle for the first time.