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No, but once he gets the ok from the president, it is then up to him when to launch.

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Likely because Falken had given authorisation for both David and Jennifer to be alongside him - and the NORAD officers looked to Falken's testimony that both were important to have alongside him, in reaching the NORAD control room before a lockdown.

To showcase the $1m film set

In the early 80's, Wordperfect was the best known word processor (there were only a few) and it was not pervasive like word processors are today. In addition, the typewriter could create professional looking document, while the only printers at that time were dot matrix, which had pretty bad quality.

There's a brief moment in the film where McKittrick's programming team are talking with the government officials about how David did it: somehow a phone line got "crossed" in Sunnyvale, California, the same city where Protovision's headquarters were, which is the same company that David was trying to hack into to find out more about their new lineup of games coming out soon. Actually David used a password left by the WOPRs programmer.

One of McKittrick's team has a quick line where he says "... the phone company screwed up!!"

It's called Galaga, an early 80s arcade game. The objective is to advance through many levels by using a fighter craft to destroy alien invaders and to score a high hit percentage vs the number of shots you fire. More info on the game is here.

In addition to looking for Protovision, David was looking for other businesses in the area that could be useful in his hacking. As we see, while Jennifer looks on, he finds a bank & Pan American airlines, which he immediately hacks into and makes a reservation for himself and Jennifer on a future flight.

When Jennifer points out that dialing so many long-distance numbers can be expensive, David is unconcerned because he probably already knows how to erase the call records in the phone company's system.

Because of the film, the practice became known as "war dialing".