Jack's Dad alive post plane crash?

This is my first post so I apologize if this has been brought up in the past. I was just watching "Through the Looking Glass" and I picked up in the scene where Jack shows up to work post flight 815 crash, and is being lectured by the head of surgery at the hospital. He asks Jack how much he had to drink today and Jacks reply is "Go get my father upstairs and see who's more drunk" or something of that nature. Now is this a huge screw up in the Lost timeline or am I missing something?

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