The news on Neighbors kept improving as the weekend progressed.  After securing a better than expected $19.6 million debut on Friday, the Universal comedy wound up with $51 million for the three-day weekend.  That’s the second-highest debut ever for an original R-rated comedy, and beats the film’s most optimistic pre-launch projections by almost $20 million.  The Amazing Spider-Man 2 fell to second place, down an estimated 59% in North America as its international grosses crossed the $400 million mark - so it's a good news/bad news morning for Sony.

Full story after the jump.

The box office loves a success story, and there’s no doubt that Neighbors is that story this morning.  One week ago the outside projection for the comedy’s first weekend was $35 million – in the range of recent R-rated comedy hits like Identity Thief and 21 Jump Street.  Instead, Neighbors pulled in an estimated $51 million, a figure that puts it close to the all-time highest debut for an R-rated (non-sequel) comedy.  That title still belongs to Ted, which earned with $54.4 million in 2012.  And, just for the record, Ted, Neighbors and Identity Thief were all distributed by Universal.  The studio is having a remarkably good year, launching four first-place debuts with Lone Survivor, Ride Along, Non-Stop and, now, Neighbors.

Along with its impressive opening, Neighbors looks strong from a number of other perspectives.  First and foremost, its budget: the comedy cost a reported $18 million before marketing so, technically, it’s already profitable.  Compare that to The Other Woman, which has been holding well in the top three since its debut last month.  The Fox comedy cost $40 million and opened with just under $25 million; so if The Other Woman is a hit, Neighbors is a big, giant hit – at least at this early stage.  Neighbors also marks career highs for both Seth Rogen and Zac Efron.  Rogen’s previous best was 2011’s The Green Hornet, with $33.5 million, while Efron’s high was the $42 million of 2008’s High School Musical 3.  Both actors have had bigger openings from their animated voice work, however.

If the news for Neighbors was all good, the headline for The Amazing Spider-Man 2 was more mixed.  A steep drop of 71% on Friday levelled off to a more standard weekend decline of 59%.  That’s better than the -61% that Spider-Man 3 experienced in its second outing back in 2007 and is just a bit steeper than recent comic releases, including Captain America 2 (56%), Thor 2 (57%) and Iron Man 3 (58%).  Of course, where ASM2 looks weakest is next to its own predecessor.  In its sophomore frame, The Amazing Spider-Man was down just 44%, a hold that helped the reboot turn a not-quite blockbuster opening into a strong $262 million by the end of its domestic run.  It remains to be seen if the sequel, which has not been as well-received as ASM, can reach that mark in North America.  What is beyond doubt is how well the film continues to do abroad.  On Sunday, ASM2 crossed $400 million in international receipts, bringing the film’s worldwide total to nearly $551 million.  So just $200 million to go before the big-budget sequel starts to turn a profit!

Though Neighbors obviously stole the spotlight, this weekend did host two other new releases – both aimed at decidedly different audiences than the adults-only comedy.  Legends of Oz: Dorothy’s Return is an animated sequel to (surprise!) The Wizard of Oz.  From the unknown Clarius Entertainment, Legends of Oz launched in 2,575 locations and brought in just $3.7 million.  That’s just a bit higher than the $3.6 million of the Weinstein Co.’s infamous animated flop Doogal, from 2006.  Interestingly, Legends of Oz received an almost perfect ‘A’ CinemaScore from the audiences who did see it, so it looks like families chose to skip this off-brand Oz on principle alone.

Coming off much better this weekend was the PG-rated comedy Mom’s Night Out, from TriStar.  Marketed to the same Christian audiences that made Heaven is for Real and God’s Not Dead breakout hits this spring, Mom’s Night Out opened to an estimated $4.2 million from 1,044 locations.  That looks weak, especially when Heaven is for Real is still holding strong in the top five after four weeks.  But Mom’s Night Out actually had a higher per-theatre average ($4,023) than any top ten film besides Neighbors and The Amazing Spider-Man 2.  The film also has a reported budget of just $5 million so, provided it pulls in some Mother’s Day business on Sunday, it could still turn a small profit.

Overall business was down slightly this weekend from the same frame last year, when Iron Man 3 was enjoying its second week on top of the box office.  Next weekend brings us the latest incarnation of Godzilla, which, at this point, is expected to bring in about $75 million.  But Neighbors is proof of how difficult it is to predict a film’s opening weekend in advance.  At this time last week Neighbors was expected to open in second place with about $30 million.  There is no doubt Godzilla will wind up on top, it’s the number attached to the win that's a question mark.  Check back next Sunday to see how it all turns out.