This account made me think about some of those Missing 411 stories. Especially the part about his Dad being motionless staring at a fire with no smell. It sounds almost like a time dilation bubble out of a SciFi movie or theoretical quantum mechanics lecture; a localized area where time moves at a different speed.
Many of the Missing 411 reports have a common theme where a person disappears suddenly even when other people are around. In this story I'd imagine that to his Dad the time between the Son getting up and coming back shaking his shoulder was just a few moments while that time period was much longer for the Son. In that scenario the Dad could have watched the Son walk a few steps into the woods then "disappear". From the Dads perspective he would think the Son could not be very far away because he was only gone for 2-3 minutes, but in that time the Son could have experienced a time frame of an hour or more and be too far away from any sensible search pattern.
The Missing 411 stories also seem to happen in close proximity to water, which was also a key factor in this story.