Former Iron striker Andy Keogh had levelled for the home side, converting a penalty after he had been felled in the area, but the Football League newcomers had more stomach for the fight.
It caps an impressive start to life in the League for the Lancashire side, who had claimed the scalp of Preston in the first round of the competition.
And McCarthy accused his players of believing the hype after they were touted as promotion material following an impressive start to the new Championship campaign.
"The exit is deserved, we were out-fought and out-played," he admitted.
"There was some amateurish defending. Was the first goal a penalty? Well we shouldn't have given the ball away the way we did.
"There were enough mistakes made for that goal alone to write a book on mistakes. Then, after getting back into it, to go and lose is an outrage.
"Maybe expectations are weighing a bit heavy. We have designs on being a Premier League side and we looked as far removed from that as Morecambe are."
