Solitaire beats Bond at gin rummy. This makes her one of the few people to ever beat James Bond at a card game, much less at anything, in either the books or movies.
Bond escaping the alligator lake by running along their backs. The stunt was actually done with real gators by their actual owner.
The sweet boat chase. It was so spectacular with its high speed racing and big jumps over land that it was mentioned in the Guinness Book of Records for years after for longest boat jumps even after the technical distances were surpassed.
After dispatching Tee-Hee on the train with surprising ease, Bond cozies up to Solitaire in their compartment. However, the camera reveals Baron Samedi sitting on the front end of the engine, bellowing a deep booming laugh. Close-up on his face, as the theme song kicks back on for the end credits.
Kananga/Mr. Big's plan is not only comparatively restrained for a Bond film, but actually very clever: by flooding the market with free heroin (which, with his personal wealth and political position, he can afford to do), he'll not only create thousands of new addicts, but also drive the majority of his competitors out of business, leaving him to reap benefits of a monopoly.
Bond evading the police in a double-decker bus. Complete with shearing the top section off. Made even more impressive by the fact that Roger Moore did some of his own stunt driving.
Bond's desperate gambit with the limpet mine on Mr Big's boat. As he and Solitaire are keel-hauled, he knows Big is dead either way, but he's praying the mine goes off before the boats pulls them over the jagged reef where the barracuda will eat them alive... and it does. But only barely. If a John Barry theme doesn't start playing in your head at that moment...