The scene where they reference other movies is just establishing the in-universe rules for time travel. Specifically, that when they time travel, they're actually traveling to a different branch of the "many worlds" tree of possibilities. This is a real theory that says that every time a quantum waveform collapses, what's actually happening is that the universe is splitting into multiple copies, one for each possible outcome, so that all the possible outcomes actually happen. So their time travel is actually finding a different universe that is identical to the one they want to travel to. The in-universe consequence of this is that, since they're going to a whole different universe, any changes made there don't affect the universe that they came from.

It's accurate in that the "many words" theory is a real (but unproven, possibly unfalsifiable) theory. It's not accurate in that there's no reason to think you could get from one universe to another. And maybe questionable that a universe identical to your own universe's past actually exists as one of the many words.

It's also internally inaccurate, since Steve Rogers travels to the past and then apparently just waits around to show up in the present again, which is exactly how they said it doesn't work.