a long time ago they used to auction an engine room tour on the four day, but rumor has it that someone brought their kids and one got hurt. So it was discontinued long before 9/11. Since 9/11 no one is allowed behind the scenes because of the extra secruity. Hence no more bridge tours.
There is a making of the Magic on the 7-day 20 minute video in the Navigation Series. But I'm guessing you were asking if there was a behind the scenes tour.
We have pictures of the engine room on our site, since we were one of the "lucky" ones before the tours were discontinued.