It was on side.
But what really undone them wasn't the officials. Being at home (fortress County), in a must win game for promotion and not mustering an attack until the 40th minute? Even then they contrived a goal, all lucky glancing touches, everything fell right. So you can't say they were out of luck. One disallowed goal burst their balloon? They got away with a lot of fouls and gamesmanship over both games.
The bottom line is, they were second best across the pitch in both legs. I think we would have won if the goal had been allowed. I think we would have won without the first leg penalty. I think we wanted it more and they never really coped with us in both legs. Nolan knew it, over active on the touchline shouting at officials, Robins calm, pointing, winking, attending to the finer points for his players.
Another poster mentioned this, but Bayliss ignoring Nolan holding the ball for a throw in...totally undermined Nolan...Bayliss body language; we are in control, we are playing at our pace whether it incurs extra time or not, you are the one holding the ball, most possession you have had all game numpty!