Army guys on an aircraft carrier go through a portal in the ocean and wind up in World War II, where they shoot down a Japanese plane (wuh-oh!) and then have to decide whether to win the war for America and probably destroy the universe because of space–time problems or just hang out and then go back to the future. They choose the second path (obviously), but maybe this one guy stays behind and then ends up pretty old.
You built a time machine...out of an aircraft carrier?
* This movie is called The Final Countdown and is from 1980, and as far as I can tell, my summary of it is pretty complete and accurate. What is this movie, 20 minutes long?