Other mistake: In the scene where Tom Hanks and his son are riding in the car and Hanks is telling about the aunt in Perdition, a shadow is casted onto the hood of the car. However, the reflection of the clouds in the windshield never get blocked out.
Other mistake: At the time Tom Hanks hides behind the chest when being shot at by Jude Law, it doesn't seem possible that at that close range, he could hold the chest lid up against multiple shotgun shots.
Answer: We never find out. But, if I remember correctly, in the graphic novel, the aunt is killed prior to the (O')Sullivan's arrvial (although not by Maguire; that character was created specifically for the film).
Cubs Fan ★