Continuity mistake: When the bus is coming to pick up Alfre Woodard as she is finally meeting her son, we see Robert Downey, Jr. briefly touch her on the shoulder. Since she's a soul, this is impossible.
Continuity mistake: Towards the beginning of the movie, little Thomas is in the school restroom singing with his "imaginary friends." When he comes out of the stall to wash his hands he doesn't turn on the water but just rubs them under the spout and keeps on singing.
Factual error: When Thomas is at the race track and putting a bet down, the money he's holding is newer, even though the scene takes place in the 60s.