The Mystery Science Theater 3000version of the film deletes an explanation that GenCorp sold the power of Time Travel to the US government, who ruined history by going back in time to win wars it had already lost. While its inclusion helps explain the idea of weaponized time travel, this just opens a huge can of worms. For one thing, the wars the US has actually lost were not lost due to a lack of fire power note Korea ended in a draw to avoid nuclear war with China, Vietnam ended because of negative public opinion, etc., so they wouldn't really have any more advantages in altering the past. For a bigger plot hole, wouldn't this have started having effects on history immediately, thus making Nick and Lisa aware of the "new" history? And lets not forget all the minutemen that Nick got killed by J.K. (though whether they would have stayed dead after Nick altered history again is not explained). The movie seems to never set any consistent rules for its time travel, nor try to establish Timey-Wimey principles, so it can really make your head spin if you try to work them out.
I didn't see the uncut version, but maybe the wars that they lost were ones that had yet to happen to the US, in the next fifty years, and not ones like Vietnam.
Well, Nick never gave the demonstration, so no one died, but how did he know in the first place it was bad if he never went, so he'd have had to experience the entire adventure to know not to give the demonstration, but then he wouldn't have not known to make the demonstration, so he'd give the demonstration but then he didn't give the.... BOOOOOOOOOOOOOOM!
The advantage to altering the past is not the added firepower, but the added knowledge. Tell the US Commanders to fortify against the Tet Offensive and that whole war potentially takes a decisive turn for the Americans, for one example.
However, there is still one that isn't explained in the original cut: where the hell did Nick get that gun?
Here's one; J.T. wants to leave Nick and Lisa on a Revolutionary War Battlefield so they'll just be 'unidentified war dead.' Why not simply take them father back to, say, the year 1000 AD and just leave them? Or shoot them, if he really wanted to. Then they would be out of the way and he wouldn't have the problem of historical records mentioning the existence of blue-jeans and plaid in the eighteenth century. Or pissed minutemen attacking him.
Hope those revolutionaries that Robertson shot weren't important and were supposed to die that day anyway.
Why does Nick destroy the time transport? Does he not trust himself not to destroy the future? Does he think himself incapable of keeping it a secret? He seemed to be doing fine up until he decided he needed more cash and spilled the beans.
It's probably exactly what you said: after seeing the risks of time travel firsthand Nick no longer trusts anyone with that power, not even himself.
And for that matter, why did Nick need the money? Usually, when an inventor needs cash, it's to create or refine a prototype. Nick's time transport worked perfectly and reliably. Why the need for the sudden influx of cash? Unless flying through time ate up the airplane fuel?
Maybe he wanted to make it smaller or put it on something more stable than a light aircraft. I mean, if he accidentally time travelled into a raging storm he could be completely boned.
I was going to ask why Gencorp and not a university whose science and history departments would consider the transport a godsend (and would keep things under wraps)... but then I realized Nick is kinda stupid.
He can't drive? He sure pulled out of the parking lot without a problem... I guess he just can't drive straight?
Even more confusing because he can fly a Cessna and pilot a speedboat just fine. Then again, he didn't say he couldn't drive, he said "I don't drive," so maybe Nick chooses not to drive as a matter of principle, and he just briefly forgot about that fact. Again, he is pretty stupid.