"Blackmail" Is Such an Ugly Word: In the story, the Ox isn't too happy when he learns the Rat was only pretending to drown in order to take advantage of his kinder nature. He accuses "You tricked me!". To that, the Rat insists "Nope, I outsmarted you!"
Broken Aesop: Despite exercising and preparing so hard in the story, the rat had to resort to cheating (via taking advantage of the ox's better nature) in order to win the race. Dongwa and Sagwa even point this out by the end of the episode.
Underdogs Never Lose: Despite being the smallest of the animals, the rat ultimately wins the race and comes in first. Ironically enough, Dongwa's animal (the monkey) loses to a goat and Sagwa's animal (the dog) loses to a rooster.
Wounded Gazelle Gambit: The rat sees that the river is the only obstacle that keeps her from winning the race. Notably, the ox is the only animal who doesn't bother stopping for a drink like the others, so she pretended she was drowning so the Ox would take her safely across the other side. Later, she reveals she was never really drowning, but was standing on a rock the entire time.
The Four Dragons consists of:
Bookends: The episode begins with Nai-Nai finishing the story of the titular Four Dragons. At the end of the episode, it's the Miao Siblings and Fufu who conclude the story for the Alley Cats.
Jerkass: The Jade Emperor in Sagwa's telling of the Four Dragons. It was within his power to end the famine that would otherwise lead to countless mortals perishing. But no, he chooses to break his promise to the Four Dragons and further delay the rain out of stubborn Pride.
Jerk with a Heart of Gold: The Alley Cats start out thinking it babyish to enjoy the story of the Four Dragons, but afterwards find the story enjoyable and ask for another story.
Broken Aesop: Despite exercising and preparing so hard in the story, the rat had to resort to cheating (via taking advantage of the ox's better nature) in order to win the race. Dongwa and Sagwa even point this out by the end of the episode.