Indeed. It's not always easy when they show you the replay once and then it's just a mess of stuff happening around.
Unfortunately these things seem to happen in Chelsea v United matches. When this sort of thing happens in matches between two of the top teams, it's going to cause a lot of emotion to fly around. It's almost like an El Clasico match.
I can remember Drogba's (quite clearly) offside goal at Old Trafford not too long ago, that was a bad one!