In the credits at the beginning of the episode, "Tim Griffin" is listed twice.
Tim Griffin is listed twice in the opening credits and Gary Grubbs isn't listed at all. Grubbs is a great actor.
The ages of the two brothers don't completely make sense. First, their mother claimed that the boy's father died "six years ago when Gil was 11", which would make Gil 17. John is clearly the older brother and introduces himself as such to Hunter. In the last scene of the episode, which was implied to take place a while after Gil's funeral, John claims to be 17.