The New Kids on the Block lunchbox is a reference to Indigo Children. Lee Carroll and Jan Tober wrote _The Indigo Children: The New Kids Have Arrived_ in 1999. "Born to Run" also hints at Indigo Children.
If they buried the capsule in 1989, there would be 15 more years before Kate would crash on the island. ( Numbers )
The model plane is Kate's constant.
The "New Kids on the Block" lunchbox could be seen as foreshadowing that Kate is to be one of a group of new arrivals on the island. Jacob's visit to her at the moment she stole it adds weight to this.