I'm still trying to wrap my brain around the version of time travel in The Tomorrow War. Spoiler alert, I guess: If they save the day in the end, the future won't have that Big Problem, which means the people in the future won't have to go back to the present to warn everyone, which means that World Cup Final won't be interrupted and we can find out if Brazil won in Qatar in 2022.
The Tomorrow War is a big-budget sci-fi action film that ended up on Amazon (who apparently paid $200 million for the opportunity). It features time travel, and I understand it's always hard to work on the logistics. Each book or movie has its own rules, and I'm fine with that. The explanation doesn't even have to make sense, but it should be relatively consistent with the world of story. Philip K. Dick often has parallel universes going, and they are often confusing, but he'll take the time to explain things (I'm thinking of Now Wait for Last Year, when the elected leader of Earth is always sick and always surviving at the last minute ... eventually we find he uses a powerful drug to move through time, with alternate versions of himself stepping in to ... heck, it really is impossible to get, it doesn't really matter, we just know "drugs" and "parallel universes" and that's good enough).
The Tomorrow War basically punts on all of this. There is a brief explanation of how draftees from the present are chosen to fight aliens in the future (they all die in "real life" before that future date, so they'll never be in the same time as themselves, which is a standard paradox of these stories). And that's it. Chris Pratt's hero goes into the future, he fights aliens, he eventually returns to his own time, and anything he and others accomplish in the future which change things in the present are basically ignored.
Here is the trailer that explains the concept:
That Big Problem we find out about in the trailer (and early in the movie as well)? Return to my opening paragraph after you've seen this movie, and tell me who won that World Cup match.
The Tomorrow War isn't junk, but it's not very good, either. You'll find yourself ticking off homages/steals: Aliens, Starship Troopers, 1951's The Thing, any time travel movie you've ever seen (Looper). It lacks the lunacy of Arnold's Total Recall, which did a good job of capturing the unsettling feeling of people in a Philip K. Dick story. They pile on the action scenes, and they're OK, nothing special. The cast is nice ... Pratt makes a good hero, and there's Yvonne Strahovski, J.K. Simmons, Betty Gilpin (wasted), Sam Richardson, Edwin Hodge, even Mary Lynn Rajskub. It's too long for the pleasures it offers, but if you have 140 minutes to spare, you will probably be satisfied. Don't expect anything more, however.