Here is one for you, during the future flashes, when Jack is being questioned by the other doctor, he tells the doctor to go get his dad and see which one is more sober. Well, Jack's dad died in Austrailia and Jack was bringing his body back on the plane that crashed. So, how could the doctor go and get Jack's dad to see which one was more drunk if his dad was already dead?
2 ideas. Either the opiates Jack was on just had him confused. When Jack challenged the doctor, the doctor didn't reply "Ok, I'll go get him." Or, Jack's dad eventually appears on the island, in the future, through some island voodoo, and gets rescued with everone else.
I am gutted the season is over but I was always more into comic books than Treasure Island 