Other mistake: Whilst the main character is having a 'talk' with the general, the world clocks on the way show 3:50 on time 1, and 3:49 on time 2. (01:25:10)
Factual error: During the opening credits a newspaper is shown welcoming the "49th" state. The movie is set in Hawaii and Alaska is the 49th state. Hawaii gained statehood in August 1959, Alaska in the January of that year.
Mitchell: Did you almost marry my mom?
Brian Gilcrest: Many, many times.
Mitchell: Why would anybody break up with my mom?
Carson Welch: The future isn't just something that happens. It's a brutal force with a great sense of humor that will steamroll you if you're not watching.