This movie makes no sense. *Spoilers*
Why would someone flee a traffic accident if he was sober and had no legal problems? That makes zero sense.
I have an idea. They should've alluded to Reznik being under the influence of alcohol by showing him drinking while fishing. That would've tied in the photograph and gave a logical reason for him leaving the scene of the accident.
Instead we're supposed to believe a guy hits a kid, drives off for some unexplained reason, then feels bad about it. Yeah, not buying it.