Corrected entry: At the end, the suggestion to unplug W.O.P.R. to prevent the missiles from being launched was actually the right suggestion. Given that W.O.P.R. was guessing the launch code by brute force, the actual order to launch the missiles wouldn't be given until the launch code was determined and therefore the silos would not interpret anything until they received not only the order to launch but with the right launch code.
Corrected entry: At one point the General suggests unplugging the system so the missiles won't go off. McKittrick says the WOPR would interpret that as a shutdown and launch the missiles anyway. But if that were the case then why didn't WOPR launch the missiles when David shut down the game from his home earlier in the film?
Correction: The General and McKittrick don't know the computer is simulating a game and think this is the real thing. The computer won't launch missiles even if they did unplug, even though McKittrick thinks that. That's why it didn't launch anything when David shut off the game either.
Exactly right. Joshua knows it's a game at the house. McKittrick thinks the whole thing has been real at the time je makes the comment - which actually raises the question: why didn't McKittrick put 2 and 2 together at that point and realise David was telling the truth about the game? (although in the narrative of the film it is, at that point, irrelevant and would likely be out of step to go there in the story).
Corrected entry: McKittrick tells the General at one point that the missiles won't launch unless in DEFCON 1. However towards the end of the film, everyone in Norad is in a panic when seeing Joshua getting the code and about to launch the missiles itself. Why then wouldn't anyone in Norad just get out of DEFCON 1 and move to any other DEFCON number so Joshua could not launch the missiles even if finding the code? Nobody with NORAD intelligence thought of that?
Correction: Joshua had full control of the system, including controlling the defense condition.
Other mistake: When Jennifer meets David in Oregon she says she drove 3 hours to get there. In the next scene they are getting off a bus to catch the ferry. What happened to her car?
Suggested correction: There are possibilities off-screen as to why. It's possible that the bus used its own private road to get to the ferry which may be closed to the public, or the parking lot may have been too expensive and they parked on a street instead and caught a bus. It's not really known, but those are some possibilities.
Corrected entry: When David calls Jennifer from a pay phone where he claims he's at NORAD in Colorado, he asks her to buy him a plane ticket from Grand Junction to Goose Bay, Oregon. NORAD is located near Colorado Springs, that has a main airport. Grand Junction is a five hour drive west through the Rocky Mountains.
Correction: He's just escaped from NORAD. The Colorado Springs airport is probably the first place they'd watch for him. David's smart enough to think of that.
Correction: He said Salem Oregon when you watch the film that's what it sounds like his destination was.
Corrected entry: The whole point of playing tic-tac-toe in the end was so Joshua could learn that the game would always end a tie. But take a close look at the second game he plays in the war room. Two "X"s and two "O"s are played in boxes where all Joshua would have to do is put the next X in the top middle box, and he would've won that game. A human could conceivably miss that, but since it was just established that Joshua was playing himself (of players "zero"), a computer wouldn't have missed such an easy move, especially since the reason Joshua plays anything is "to win the game".
Correction: This was explained in the movie. Unplugging W.O.P.R. would trigger a failsafe that would launch the missiles automatically without needing the launch codes, on the assumption that the disconnection meant NORAD was no longer operational. Given all the ways communications could be interrupted this is a stupid failsafe but, in the context of the movie, this isn't a plot hole.