I've heard lots of bullshit from blues who reckoned they were there that day, doing congas after the goal went in, taking on the Stretford End, that kind of thing.
There was no section of the ground in those days as there was no segregation. You went where your ticket said you were going to go, and unlike today, tickets for games there were easy to obtain. I went to every derby between 1972 and 1976, including that game in 1974.
I was there, and it's not a day I remember with any great affection. I saw too many people getting their heads well and truly kicked in, some of whom never moved after being assaulted, and that was red on red.
It was not a place to be advertising you were a blue, let's put it that way, and I can well understand your friend taking cover in the scoreboard end toilets.
Of the many people I have met over the years saying they were there, I have only met two who I have believed were at the game. One said they were so shit scared they kept very quiet and left, and the other said pretty much the same thing.
I also kept very quiet as well.
As for getting away after the game, it was probably easier then than it is now due to there being no away section which could be targeted by the home fans.
You didn't wear colours at away games in those days, so you could just blend in, and I didn't have any problems going home.
It may seem a bit of a giggle on youtube these days, but it was without doubt the scariest moment I have ever known at a football match in my life.