Plot hole: How could it be that Monty could possibly know exactly that Joe and the ex-wife were driving and where they would be to time that collision perfectly? A bit odd in reality to time a plan like that.
Plot hole: When Mr. Jeffries finds out that Evan is named August Rush too, he goes to the Central Park concert and sees Evan onstage, however he couldn't know that Evan was having a concert, or even that Evan was at that place at that time.
Suggested correction: There were streetlight banners all over Central Park with August Rush's name on them (and presumably the Philharmonic had flyers and other ads with August's name on them). So it's certainly conceivable that Jeffries recognized the name from an advertisement.
Plot hole: Reverend Frank reveals that he once married an immigrant from his congregation so that she could stay in the country after her application for asylum was rejected. No immigration official would ever have believed such a marriage (to a priest!) to be genuine and her application of leave to stay would have been rejected.