Back-at-the-Beginning Track

The Back-at-the-Beginning Track is a treasure in Pikmin 4. It is actually a piece of a toy train track.

Drafty Gallery
There is a Back-at-the-Beginning Track on the far west of sublevel 2 of the Drafty Gallery. To access it, jump into the geyser in the central northern point of the sublevel, and then to the geyser after that one. To collect this treasure, you must throw 7 Pikmin at it.

Subterranean Swarm
There is a Back-at-the-Beginning Track in an alcove on the western edge of sublevel 3 of the Subterranean Swarm. It is guarded by a Horned Cannon Beetle, which should be defeated before attempting to collect it. To collect this treasure, you must first destroy the sticky mold covering it, then throw 7 Pikmin at it.