So, specifically, what part of the investigative report was falsified?
Nothing specific - just tinged by the close relationship between McCain’s father and the lead investigator, taken in conjunction with the odd/troubling revelation of McCain’s immediate departure for “R&R” in Saigon - before funerals for the dead the following morning. Details like this lend very negative optics to the sanitized formal account.
Product of a military heritage, McCain’s low achievement rank at the academy & having crashed two planes and flown a third into power lines in his short Naval career draws one to look beyond the sanitized versions of McCain’s background.