Mullins, whose loan club have won five out of six matches following his arrival a month ago, attributes much of manager Brian McDermott's men's success to the side's "great" team spirit.
"There's great togetherness," he told the club's official website. "As soon as I walked into the dressing room I could see that.
"You see Adam Le Fondre pop off the bench and score two goals. It's fantastic. It's a great spirit and it shows on the pitch.
"I had to wait for a chance and I got it after the injuries, but before that the midfield had been brilliant. Mikele Leigertwood and Jem Karacan have been first class."