Marty arrives, right on time
I wrote a piece of software to start playing Back to the Future Part II at exactly the right time, so that the moment they arrived in 2015 was the precise moment we were watching it happen. The date and time in the film matched the date and time in reality.
I also made a clock and countdown timer to go with it. In the video, the timer hits zero as soon as the DeLorean appears in the film.
Marty arrived at 4:29pm on 21 October 2015 in California (PDT). Here in Perth, Australia, that was 7:29am on 22 October 2015 (AWST).
Watch the actual moment on YouTube →
The visiting Marty has long since gone back to the past. This clock now counts the time since his arrival; the replay opens the original two-line countdown in a new tab, starting one minute before arrival.