The Vat of Acid Episode

Background

Rick and Morty meet alien gangsters at a factory to exchange valuable crystals. When the gangsters betray them, Rick fakes their deaths by jumping into a vat of fake acid, but the gangsters stay to discuss their feelings and test the vat, and Morty's impatience reveals the ruse. Morty harangues Rick for never taking his ideas seriously and goads him into building a portable save-point remote that can undo mistakes.

Morty uses the remote to commit crimes and pranks without consequences, then falls in love with a girl and, stranded in the mountains after a plane crash, chooses to call for rescue rather than reset. After the rescue Jerry unintentionally activates the remote, and Morty cannot recreate the relationship. The episode received largely positive reviews from critics, who praised its storyline and emotional depth.