Even though it was only number three in box office numbers for the long holiday weekend, The Dark Knight gets most of the buzz—its additional $11 million put its cumulative US and Canada total to $504.7 million. That makes it only the second film in history to achieve those numbers. Titanic was the first.

It was Tropic Thunder that once again came out on top this time around, with an additional $14.3 million. The $86.8 million the R-rated comedy has achieved so far is just shy of its reported $92 million budget. This is Tropic Thunder’s third week in the number one slot.

It came as a bit of a surprise to the critics that panned Vin Diesel’s Babylon A.D. that the sci-fi thriller opened in second place, with $12 million. Even though it was runner up for top grosser over the long weekend, Babylon A.D.’s numbers were a bit of a disappointment for Fox, which had hoped for $17 million at the very least.

In fourth place was the Playboy sorority comedy House Bunny with $8.3 million, which only dropped 43% from last weekend, giving it $29.8 million total so far. Not bad for a film that ‘only’ cost $25 million to make.

And the new thriller Traitor, starring Don Cheadle, opened in the fifth slot with a better than expected $7.8 milllion, for the four-day weekend. Adding what it made between Friday and when it first opened on Wednesday, its total is $11.5 million.

If the numbers of the top five films sound a little low, it’s because they are. Labor Day Weekend grosses this year are 18% lower than they were this time last year. It could be because the current wide releases over the holiday weekend were exceptionally bad, according to critics.

In addition to the premiering pix already mentioned,  (Babylon A.D. and Traitor), the comedy spoof Disaster Movie opened in seventh place with $6.9 million, and College did even worse, debuting outside the top ten at number 15, with a paltry $2.116 million.

Industry insiders have little hope for next weekend to break the downward spiral in box office receipts. The only big film to open next weekend is Lionsgate’s Bangkok Dangerous starring Nicholas Cage.