Box-office analysts are betting that The Mummy Tomb of the Dragon Emperor will take down The Dark Knight this weekend. Noting that the last Mummy movie opened with $68 million, they say that even if the latest one takes in $50 million, it would still likely become the weekend's top film. (The Batman sequel took in $75.2 million last weekend and would have to fall less than 33 percent in its third weekend to stay above $50 million -- something the analysts suggest is unlikely. They're predicting it will gross about $35-40 million.) The only other film opening in wide release is the Kevin Costner comedy Swing Vote . It's expected to take in less than $10 million.