The movie is set over a period of ten years but none of the characters seem to age at all. This is especially noticeable in the younger members of the cast. However as the film jumps in time almost from the beginning it is difficult to work how old each of the younger cast members would actually be, but this could be the film makers intention.
In one scene that takes place in 1983, Ty and Robbie are in the toy aisle of a department store examining stuffed animals as they figure out how to make better ones. On the shelf behind them is the board game, "Ticket to Ride", which wasn't published until 2004.
The Flaming Lips' "Waiting for Superman" is playing at a roller skating rink during a scene set in 1996. This song appeared on the album "The Soft Bulletin," which was released in 1999.