What is the name of the train that runs in Riley's mind?

The train that runs through Riley’s mind is called the Train of Thought.

It is a whimsical mental transit system in *Inside Out*, carrying ideas, daydreams, and other thoughts between areas of Riley’s mind and Headquarters. The train travels on a track that seems to generate itself, reinforcing the film’s playful interpretation of how thinking works.

The Train of Thought is also used to move memories around Riley’s mental landscape. Joy, Sadness, and Bing Bong encounter it during their journey through places such as Imagination Land and Abstract Thought. Its operators even stop working when Riley falls asleep, turning a familiar phrase into a literal visual gag.

The name is easy to confuse with the film’s memory-related settings, especially Long-Term Memory. Long-Term Memory is a storage area, while the Train of Thought is transportation. “Memory Choo-Choo” and similar names describe the joke but are not the canonical term.