9. Don't Blame the Writers | Mr. D tells a young John to "say hello to your old man for me." in the diner of In the Beginning (4x03), but later in As Time Goes By (8x12), this fact is changed. Dean tells Henry about how John thought that his father had ran out of him because of leaving when he was younger. This was however due to the fact that Henry travelled to the future and ultimately ended up dying there too meaning that he was never able to return to his own time, therefore Henry would definitely not have been around in 1973 as he disappeared in 1958.

I THINK ABOUT THIS A LOT