It wasn't a big surprise that Disney's new live-action "The Jungle Book" opened at No. 1 this weekend. What was a shocker, however, was just how big the latest version of Rudyard Kipling's tale turned out to be.

Going into the weekend, positive buzz for the film led to predictions that it would open to at least $70 million, $85 million on the high-end of expectations. On Sunday, however, Disney estimated that the film's opening weekend had grossed $103.6 million. That makes it the second-biggest April opening ever, beating the $95.0 million earned by "Captain America: The Winter Soldier" two years ago, and second only to last year's "Furious 7," at $147.2 million. It's also the biggest April opening ever for a PG-rated movie.

How did "Jungle Book" over-perform so much this weekend? Here are five ways.

1. Marketing

By now, Disney has mastered the art of turning its beloved animated classics into live-action reboots. But there's more than brand recognition at work here. Disney's marketers -- and director Jon Favreau -- made a point of playing up the state-of-the-art CG that allowed the filmmakers to simulate a jungle in a Los Angeles warehouse and populate it with photorealistic animals. The trailers audiences saw, and the advance stories they read, promised not just a kiddie adventure with talking animals, but also an immersive experience in a lush, exotic world on the level of "Avatar."

2. 3D and IMAX

As a result, this marked the rare film that viewers felt merited the surcharges they'd have to pay to see it in an enhanced format. It helped that 75 percent of North American theaters showing "Jungle Book" screened it in 3D. A healthy 43 percent of the movie's opening-weekend sales came from 3D tickets. It was also playing on 376 IMAX screens, good for $10.4 million, amounting to 10 percent of the total gross, and scoring another April record for a Disney feature.

And there were 463 Premium Large Format screens, for those willing to pay extra to see "Jungle Book" on a giant screen that's not quite as eye-filling as IMAX. You could also see the film in D-Box, where your theater seat lurches in response to the on-screen action. Surcharges for those tickets can be as much as $8, meaning Disney was ensured to mint money on this film wherever people saw it.

3. Timing

Remember when the summer movie season began on Memorial Day? No? Remember when it began on May 1? Well, now, thanks to hits like "Winter Soldier," "Furious 7," and now, "Jungle Book," summer seemingly begins just after spring break. Or it will within a couple of years. For now, however, April is still clear enough of blockbusters that a movie like "Jungle Book" can pretty much have the month to itself.

4. Weak Competition

This weekend's crop of new releases posed no real threat to "Jungle Book's" box office reign. Neither of this weekend's other two new wide releases opened on more than 2,700 screens, compared to 4,028 for "Jungle Book." "Barbershop: The Next Cut," a sequel in a comedy franchise whose last installment came out 12 years ago, debuted in second place with an estimated $20.2 million. That's below expectations and also shy of the $24.2 million opening weekend for 2004's "Barbershop 2: Back in Business." ("Cut" came in with less than the opening weekend of the original film.)

As for Kevin Costner's new thriller, "Criminal," no one expected it to do more than about $8 million, but it fell short with $5.9 million. It didn't even make the top five. Opening in sixth place, it is Costner's lowest premiere weekend since since 2005's "Rumor Has It."

5. Four-quadrant Audience Appeal

One potential weakness in "Jungle Book" -- had Disney stayed close to the 1967 cartoon -- is that it's an awfully male-oriented story, with no female characters of any significance, or even speaking parts. Favreau and his team changed that by making one male character (the python Kaa) female and boosting the role of another (Mowgli's wolf mother, Raksha.) Scarlett Johansson voices Kaa (above), and Oscar-winner Lupita Nyong'o voices Raksha. Making the movie more inclusive seems to have paid off at the box office, since Disney exit polling showed that 51 percent of the viewers were female.

Favreau and his team also made sure the movie appealed to more than just kids. Celebrity voices (including Bill Murray and Chistopher Walken), an air of real danger in Mowgli's confrontations with predators, and nostalgic shout-outs to the original cartoon (including such songs as "Bare Necessities" and "I Wan'na Be Like You") all helped to draw grown-up viewers. According to Disney, some 43 percent of ticketbuyers were adults seeing the movie on their own.

Of course, what ultimately sold the movie was its execution. Critics raved, giving "Jungle Book" a 95 percent fresh rating at Rotten Tomatoes. Audiences loved it just as much, judging by the A CinemaScore, indicating very positive word-of-mouth. So: a good movie will draw audiences of all ages and both sexes off their couches and into the theaters -- and even inspire them to pay extra for an enhanced viewing experience. Who knew?