S4E8: The Vat of Acid Episode

In "Rick and Morty" Season 4, Episode 8, things get wild as Rick and Morty find themselves inside the story-train, a literal train ride through a narrative device. The episode is an exercise in meta-commentary on storytelling, but let's stick to the events. The duo encounters various bizarre scenarios, including battling a group of fascist teddy bears and dealing with the story's villain, Story Lord, who wants to harness the narrative energy to break out of the train and into the real world. Rick and Morty end up using the power of storytelling against Story Lord by creating increasingly absurd scenarios until they derail his plan. In the end, they escape by exploiting a literal deus ex machina — buying a ticket out of the train with a token given to them earlier. Back in the real world, it turns out Morty was playing with a toy train given to him by Rick, who wanted to teach him about narrative structure. The episode closes with Morty still not grasping the lesson while Rick is more interested in selling the toy train as merchandise.