Alvin and the Chipmunks (1983)

S5E1 Back To Dave's Future

After a thrilling spin on a merry-go-round, the Chipmunks find themselves transported to 1962, where they encounter a younger version of Dave. He reveals that without their assistance in an upcoming band competition, he’s destined to lead a mundane life as an accountant. Just as they start to help him, the boys are whisked back to the present. Alvin is left questioning whether their time travel was real or just a result of a bump on the head from falling off the ride.