Box office observers believe director Rob Cohen’s “Dragon Emperor” has a good shot at coming in No. 1. Parents will likely feel more comfortable taking younger kids to see the pic than to the darker “Knight,” even though both are rated PG-13.

Nevertheless, “Dark Knight” remains a juggernaut as it heads into its third session. Through Wednesday, the domestic cume was a whopping $342.7 million and will likely hit $400 million by Monday or Tuesday. No other film has grossed as much as quickly as this Batman sequel.

Depending upon how much it declines from last weekend, “Dark Knight” could see a gross in the $35 million-$40 million range. Tracking suggests “Dragon Emperor” could pull in more, but nothing is a given in the face of the huge interest in “Dark Knight.”

The weekend’s other new wide release is Kevin Costner political comedy “Swing Vote,” which Disney takes out in 2,213 runs. Tracking doesn’t spell good news for the pic’s box office potential.

The domestic specialty market sees several new players, including Lionsgate’s horror-thriller “Midnight Meat Train,” which unspools in 102 theaters in key markets.

Sony Pictures Classics opens Courtney Hunt’s drama “Frozen River,” starring Melissa Leo and Misty Upham, in seven theaters in Gotham and Los Angeles. The Sundance fest entry revolves around two women who are caught up in the illegal immigrant smuggling trade.

IFC opens “In Search of a Midnight Kiss” in two theaters in New York.

Among the more commercial fare, Costner himself financed “Swing Vote” before the Mouse picked it up. Pic, which cost under $30 million to produce, centers on a man indifferent to politics whose vote will decide the presidential election.

Directed by Joshua Michael Stern, “Swing Vote” also stars Madeline Carroll, Kelsey Grammer, Dennis Hopper and Nathan Lane. Jason Richman penned the script with Stern.

“Swing Vote” was drawing a 70% fresh rating on Rotten Tomatoes top critics meter as of Thursday afternoon, while “Dragon Emperor” was drawing a dismal 25% fresh rating.

“Dragon Emperor” is tracking strongly among men of all ages and older women — i.e., moms who are looking to keep their kids occupied. Younger girls are the weakest quadrant, leaving room for U’s own female-skewing “Mamma Mia!” to continue to sing sweetly in its third weekend. (That pic’s domestic cume through Wednesday was $71.8 million.)

The first two “Mummy” films pulled in strong business for Universal. “The Mummy,” released in 1999, opened to $43.4 million domestically on its way to grossing $155.2 million. “The Mummy Returns” opened in 2001 to $68.1 million and grossed $202 million domestically.

The franchise was a hit overseas as well; with the first two films each grossing $230 million at the international box office.

Foreign prospects for “Dragon Emperor” appear bright. Pic is opening at 3,559 playdates in 28 territories. Major markets are Brazil, Mexico, Russia, South Korea and Spain.

As in North America, “Dragon Emperor’s” main competish at the international box office will be “Dark Knight,” which looks likely to come in at No. 1 again.

Elsewhere abroad, Fox is widening “The X-Files: I Want to Believe” into France and the U.K. following a modest launch last weekend in 22 markets.

The frame will also see Disney expand “Wall-E” into Benelux and France and “The Chronicles of Narnia: Prince Caspian” into Germany. “Wall-E” has hit $80 million in the early stages of its foreign run, while “Caspian” has quietly gone past $230 million overseas.