CHRIS Tucker showed off his Michael Jackson impressions and sang for the cast and extras waiting each night between takes for “Rush Hour 3” at L.A.’s Galaxy Theater. One recent evening during his spiel, Tucker’s cellphone rang and he yelled out, “Everybody say hi to Charlie Sheen,” and passed the phone around so they could do just that. Meanwhile, director Brett Ratner asked around to find the No. 1 Jackie Chan fan among the 300 extras and took the young girl who volunteered up to meet Tucker’s co-star and pose for photos.