Okay, there was this kid who somehow ended up on an alien ship. He flies around and plays with some slimy alien on board and returns home to find the world has aged 30 something years without him... This is going to drive me crazy now.
The movie you're thinking of is Flight of the Navigator.
http://www.youtube.com/watch?v=XnB7rIL2fy8
That's the one! Thanks!