Continuity mistake: Near the end of the movie, the panel has JPE 1704 TKS showing, but when Joshua finds the launch code, CPE 1704 TKS is blinking on the screen.
WarGames (1983)
Ending / spoiler
Directed by: John Badham
Starring: Matthew Broderick, Dabney Coleman, John Wood, Ally Sheedy
The hacker gets the computer to stop blowing up the world by telling it to play tic-tac-toe so the computer will realize that there is no winner in a nuclear war.
Rob T Firefly
More mistakes in WarGames
David Lightman: [On the computer] Hello, are you still playing the game?
Joshua: Of course. I should reach Defcon 1 and release my missiles in 28 hours. Would you like to see some projected kill ratios?
David Lightman: Sixty-nine percent of the housing destroyed. Seventy-two million people dead. [Types into computer] Is this a game or is it real?
Joshua: What's the difference?
Trivia: Broderick changes school information from his home computer just as he does in Ferris Bueller's Day Off. Both mothers were also real estate agents.
Question: How could WOPR not know the difference between a game and real life?
Answer: While merely speculation, the WOPR is not alive and knows only what it's been programmed to do. It would have no concept of life or death, and as such would see no difference between the simulation and the real thing. That being said, an easy way to make it see the difference would be to program it to not waste physical resources. It would then see the use of all its actual warheads as less desirable.