Dr. Yes is dispatched when he accidentally scratches himself with his poison-tipped fingernail. However, moments before, he used the same nail to perform calculations after dipping it in ink, which would have washed away any poison. Even earlier, he used the same nail to slice an apple, which would have been poisoned in the process.
After arriving in the hideout of Dr. Yes, Max and 99 were wearing wetsuits and flippers. Later, when trapped in the room to be killed, they are both wearing shoes.
Although Max and 99 wear dark wet suits, when they show the footage of them underwater they are wearing white wet suits. The same thing goes for Himmel and Toulouse earlier.
When the general starts to initiate the self-destruct sequence, he turns and moves toward the inside of the room, away from the window and the panel where the self-destruct button is hidden.