Well I have seen some substitutions in pre season games but have never seen the full 11 changed at one go, then the second 11 walk right through Barca and score in less than two minutes. United 2-0 Barca.
3-1 final score, seven of United's 11 subs came through the youth team, mind you Barca did hit the post 3 times and Messi and Neymar didn't play.