"When characters exchange information they both already know, and that’s the dialogue.
“Aw, what’s up, my baby sister?”“Don’t call me baby – I’m already ten.”“I know. Because you were nine when Mom died, and that was a year ago. Remember?” “Of course I remember – you’re my older brother after all.”"
I don't recall hearing "Fortunate Son" in any Vietnam war movies other than Forrest Gump.
Then you've obviously haven't seen many Vietnam war movies.
You seem to have mixed reality with the 2018 Family Guy episode "'Family Guy' Through the Years" (presented as a compilation of old episodes from the series' "60 year run", parodying anniversary specials), Glenn Quagmire, portrayed as a Vietnam veteran in 1973, experiences PTSD-like symptoms from the incessant use of the song and "For What It's Worth" by Buffalo Springfield as audible background music during the war.
Damn Lyddy, way to bring those Receipts to be Checked! Well done.
AND the "it's all a dream", " it's all fake" endings piss me off sooooooooo much. Unless it's literally about being faked (like Total Recall).
or: Suspenseful music so you expect something bad to happen, but it doesn't. But then: jump-scare!