Kaeloo and Stumpy ask Mr. Cat to explain quantum physics to them.
"Let's Play Quantum Mechanics" contains the following tropes:
- Art Shift: The end of the episode is done in 2D.
- Black Comedy: Mr. Cat tries explaining how Schrodinger's cat worked by repeatedly pressing a button to kill Quack Quack, who keeps coming back to life, culminating in him dancing around while singing a song whose only lyrics are "Dead! Alive! Dead! Alive!"
- Mood Whiplash: Kaeloo tries flirting with Mr. Cat and seems absolutely enamored with him. Once he mentions wanting to spend time with Bad Kaeloo, however...Kaeloo: (annoyed) Don't count on it!
- Humanity Ensues: Kaeloo and Mr. Cat are briefly turned into humans while they use magic to change the world around them.
- Wham Episode: For the first time in the series (not counting "Let's Play Babysitting" since that was a joke), Kaeloo actually flirts with Mr. Cat.
