Bannan scored what proved to be a consolation with a stunning free-kick while Forest substitutes Lewis McGugan and Marcus Tudgay gunned down Villa.
“Obviously it was a great pre-season up until now, but sometimes you might need a game like this to try and learn from it,” Bannan told the Sunday Mercury.
“It’s all been going rosy and now we’ve lost.
“So we’ll take positives from it as well, but I’m sure we’ll go back to training, work hard and try to cut out the mistakes we made in this game.
“We’ve lost the game but it’s better losing now than in two weeks time at West Ham."