Jennifer Aniston in 'We're the Millers'WB

With four new movies opening in wide-release this weekend, there was a pile-up at the multiplex. In a competitive weekend, "Elysium" came out on top -- or did it? "Percy Jackson: Sea of Monsters" debuted last among the four -- or did it? Unpacking this week's tight race, not all was as it seemed, and the true numbers earned by this week's new releases offer some guideposts for what has been an unpredictable summer at the box office.

Original sci-fi is underperforming. Sure, "Elysium" premiered in first place, with an estimated $30.4 million. Still, compare that to director Neil Blomkamp's previous original sci-fi allegory, "District 9," which debuted four Augusts ago with $37.4 million. And that was when the South African director was a nobody, working with a low budget and no stars. This time around, he's a brand name, with Matt Damon and Jodie Foster headlining his $115 million movie.

The simple answer is that audiences just aren't excited about this movie; they gave it a weak B grade at CinemaScore, indicating lackluster word-of-mouth. But this summer's other original sci-fi movies have suffered the same fate, with both "After Earth" and "Pacific Rim" underwhelming at the U.S. box office. The flip side, however, is that overseas audiences rescued both of those flops and made them into international hits. The same may yet happen for "Elysium," which has already earned $10.9 million outside North America. Still, these results have to be giving the studios pause; could it be that the Comic-Con audience isn't as broad or as enthusiastic as they're purported to be?

We can't get enough R-rated comedy. That's the lesson Jason Sudeikis and Jennifer Aniston must have learned two years ago when their "Horrible Bosses" thrived during a summer saturated with raunchy-humored movies. This weekend, the pair's "We're the Millers" opened on the heels of last week's R-rated action comedy "2 Guns," yet it's the only one of the four newbies that outperformed expectations, opening with a strong estimated $26.6 million from Friday to Sunday and $38.0 million since it opened Wednesday. It helped that audiences gave it very strong word-of-mouth recommendations (as measured by its A- at CinemaScore), but it also helped that, aside from "MIllers" and "Guns," there have been surprisingly few other R-rated comedies this summer. "The Hangover Part III," "This Is the End," and "The Heat" have all earned upwards of $96 million at home and have done respectably well abroad. And for the most part, they're cheap to make. Except for "Hangover III" (which cost $103 million), this summer's R-rated comedies have cost between $32 and $61 million. Aside from studio squeamishness over the R rating, it's hard to imagine why Hollywood isn't greenlighting more such summer comedies.

Even knock-off Pixar is a draw for family audiences. "Planes" is billed as a spinoff of Pixar's "Cars" movies, but it's not made by Pixar -- it's made by Disney's own animators. The animation is cheaper and looks it; in fact, "Planes" was slated to go direct to home video. Still, audiences liked it enough (it got an A- at CinemaScore) to reward it with an estimated $22.5 million in theaters this weekend, making it the biggest August debut ever for an animated feature.

Not every franchise with magical teens is the next "Harry Potter." So it is with the "Percy Jackson" movies, whose second installment, "Sea of Monsters," opened in fourth place with a disappointing $14.6 million (estimated Friday through Sunday) and a five-day total of $23.5 million since it opened Wednesday. Maybe they shouldn't have waited three and a half years after "Percy Jackson & The Olympians: The Lightning Thief," long enough for tweens who saw the first movie to become juniors in high school. Not that there were that many; "Lightning Thief" opened with $31.2 million, toward a domestic gross of $88.8 million. Given such numbers, it's surprising that they made a sequel at all, but then, the original also earned another $137.7 million abroad. As with this summer's sci-fi, maybe foreign grosses will save "Sea of Monsters," which has already earned $9.8 million overseas. Still, the movie's a long way from recouping its reported $90 million cost and ensuring a third adventure.

No one goes to theaters to see movies about the porn industry. That's apparent from the theatrical debut of "Lovelace," which opened on 118 screens but earned just an estimated $184,000, for a meager $1,559 per screen average. The biopic of "Deep Throat" star Linda Lovelace, featuring rising starlet Amanda Seyfried in the lead, is about on track to earn what "Inside Deep Throat," a documentary about the notorious 1972 feature, earned back in 2005, which is about $700,000. That followed 2003's "Wonderland," a drama about John Holmes that barely cracked $1 million. The lone hit among the bunch is 1997's "Boogie Nights" ($26.4 million), which had an entirely fictional story, an all-star cast, and the bravura direction of Paul Thomas Anderson to recommend it. In the case of "Lovelace," it probably didn't help that the filmmakers released it on video-on-demand the same day as its theatrical debut. Usually, same-day VOD and theatrical releases enhance each other, but "Lovelace" is one movie you'd probably rather see in the privacy of your own home than pay to see in public at a theater.

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