But let's say in a multiverse scenario with only two different universes, one where the chiefs win the toss and one where the bills win it. In our universe the chiefs win because they got the ball first, but in the other the bills win because they got the ball first and those are the only two possible outcomes. Either team would have marched down the field and got the TD. Then by losing the toss, the bills lost the game because of that.
As others have said the rest of the game doesn't matter, it's in the past. Both teams make mistakes throughout a game.