Craig Woodman was then handed his marching orders for a professional foul and Nicky Forster scored the resulting penalty to make it 2-2 at the break. Murray struck to put Brighton in front for a second time, but Jon-Paul Pittman and Harrold turned the tables again before Murray's late leveller.
Hinshelwood said: "Glenn Murray did ever so well. He was out on his feet at the end. We could have taken him off with five or 10 minutes to go but we felt he needed to get in a full 90 minutes.
"I thought Elliott Bennett was outstanding - a great finish and then we asked him to do a job for us after the sending off and he was magnificent.
"We were incisive going forward, but the defensive demons came back to haunt us a little bit. I know it's a cup tie but if you score four goals away from home you expect to win the game."