Mate, you where playing a side who are failing to get into the play-offs in the Championship, you where 3-0 up, in absolutely no-way is it acceptable for that game to even get close to extra time let alone penalty's, even if the goals where lucky.
The fact that you're even defending that, shows how low Man United have come if you're even remotely happy at that performance
Also, games aren't played in 70 minutes, they're played in 90, so saying some arbitrary stat like that means literally nothing.