The Big Screen—Really Big
As TV became more common in American households, the studios needed a way to get audiences off their couches and into the theaters. New formats were developed to offer an experience you couldn't get on your tiny (pre-HD, pre-humongous screens, pre-surround sound, probably black-and-white) TV at home.
The Sound of Music was shot using a 70 mm Todd-AO process, a widescreen format that had been developed in the early 1950s and first used to film Oklahoma!. According to its developers, "TODD-AO 70mm film, plus the TODD-AO special camera, plus the TODD-AO newly developed 6 channel high fidelity magnetic sound, plus the TODD-AO 'all-purpose' 70mm projector plus the great arched TODD-AO screen equal the most revolutionary of all screen inventions, with clarity of perspective, detail and color reproduction never before achieved" (source).
In other words, there was a definite wow factor.
Problem was, you could only get that "wow" in theaters with those giant curved screens. The Sound of Music had a limited early release in major cities in theaters that could accommodate the TODD-AO format. The film was marketed to death, with exclusive engagements and reserved seating, just like a Broadway show (source).
Once people couldn't stop talking about it, the film then had a wider release.
Under the Weather, Over the Budget
With its $8.2 million budget, The Sound of Music encountered some hiccups in production that made it a little more expensive than anticipated, striking fear in the hearts of Fox executives still reeling from the financial fiasco of Cleopatra.
Shooting on location in Austria, much of it outdoors, wasn't easy. Apparently, the producers didn't know that Austria tends to be rainy during the season when they were shooting. It was especially wet that year. You don't have to be a filmmaker to know what that means: actors (many of them children) plus expensive equipment plus rain don't mix well, which means production delays and cost overruns. Production was delayed by weeks, and the crew spent days sitting around freezing and waiting for the sun to come out.
Ah, the magic of movie making.
A bunch of different estates and locations stood in for the von Trapp villa, depending on which view of the home was needed for the scene. Most interior scenes were shot on soundstages in Fox's Los Angeles studio, although some were shot in Austria. And those gorgeous Alps? They were the real deal.
Here's some fun production trivia: the film's most famous shot was extremely difficult to capture—and by that, of course, we mean that first glimpse of Maria twirling and singing on the mountaintop. That shot had to be filmed using a helicopter, and the wind from its downdraft kept knocking over the leading lady. They were close to abandoning the whole attempt when they finally got the shot. Director Robert Wise was watching from the branches of a tree, where he was hiding to stay out of the shot (source).
The movie ended up substantially over budget as a result of all those delays, leading the producers to fear that it would ultimately lose money and seal Fox's financial doom.
They didn't have to worry.