Kaeloo introduces Mr. Cat to the Sleep Train, a magical train that helps people sleep at night.
"Let's Play Sleep Train" contains the following tropes:
- Continuity Nod: It's implied that Kaeloo is still convinced that the main four don't need any friends besides each other.
- Dissonant Serenity: The episode ends with Kaeloo cheerily talking to the audience while Mr. Cat is curled up on the bed behind her, shaking like a leaf with a disturbed expression on his face.
- Laser-Guided Karma: Mr. Cat has a horrific nightmare that leaves him traumatized. When he wakes up, Kaeloo even lampshades that he got what he deserved.
