‘Thunder’ stays on top at box office

Weekend B.O.: 'Babylon A.D.' opens in second place -- DreamWorks and Paramount's holdover comedy "Tropic Thunder" continued to dominate at the Labor Day box office with three-day take of $11.5 million from 3,473 theaters, while 20th Century Fox's Van Diesel sci-fi actioner grabbed the No. 2 spot with $9.7 million from 3,390.