In the Final Countdown, what events were altered by the presence of the USS Nimitz?

Question

In the 1980 film, The Final Countdown, the USS Nimitz travels through time one day prior to the Japanese attack on Pearl Harbor.

The ship’s admiral, Admiral Yelland is faced with the dilemma: 1) stay silent and let history run its course with minimal disruption, or 2) stop the attack.

Yelland chooses to stop the attack, throwing every F-14 he’s got against the oncoming zeroes. But before the future US forces can destroy the Japanese, the time vortex returns and takes the Nimitz and its planes back where they belong.

What, if anything, did the presence of the Nimitz in the past change?

Answer 1

It's heavily implied that the time travel in The Final Countdown is stable time loop/single-timeline time travel; everything that happened during the movie already happened in the past of the characters' timeline. Given Owens/Tideman's actions, the timeline that we see at the beginning of the movie almost certainly had already had the Nimitz appear in its 1941.

So if you're asking "What changes were made from the original timeline", the answer is "none". If you're asking another question along the lines of "What changes were there from how we could have expected things to play out without time travel?", then:

Two Zeros are shot down, leading (eventually) to the deaths of their pilots and to Laurel being saved (Chapman dies, but he probably also would have died without the Nimitz). Owens and Laurel are stranded, and Owens founds a company that helps build the Nimitz, likely advances the technological level of the US further than it would have been otherwise, and gets the Nimitz to bring on the civilian observer Warren Lasky.