The tepuis and Angel Falls in Venezuela inspired the flat-topped mountains and Paradise Falls in the film. Angel Falls is the world's highest waterfall.
In the German dub, Dug is distracted by a cat instead of a squirrel, because 'Katze' (cat) is a shorter word than 'Eichhörnchen' (squirrel).
Up's score is one of many film scores to win an Oscar, a Grammy and a Golden Globe in the original score category.
The distorted perspective drawing of the house by the waterfall is a tribute to the style of Mary Blair, who brought a modern art touch to Disney animation.
When young Charles Muntz talks about bringing the monster back alive, everyone wears a hat; there are actually no characters underneath them, it is a 'Sea of Hats.' Computer animators depict large crowds this way.
WILHELM SCREAM: The dogs fall from the cliff into the river while chasing Carl, Russell, Kevin and Dug.
Carl and Russell's hometown at the end is Oakland, California. Among the landmarks shown are the Fox Oakland Theatre (during a screening of Star Wars: Episode IV) and Fenton's Creamery. Fenton's is close to Pixar's Emeryville headquarters and appeared in the film for free.
Pixar's first film shot in 3D.
Carl's house is about 150 square meters and weighs 54,431 kilos. Since an average helium balloon can lift 4.63 grams, it would take 12,658,392 balloons to lift the house. The 20,622 balloons seen during the first takeoff in the film could lift only 84 kilos.
Charles Muntz's rifle is an 1874 model Sharps; it was popular among buffalo hunters in the American Wild West, and its use is accurate. However, his use of a cartridge in a long-range rifle is questionable.
It takes a worker about 9 seconds to inflate and tie a helium balloon. Lifting Carl's house would require more than 12.5 million balloons, which would take about 3.5 years of nonstop work.
In the film, the bird Kevin loves chocolate; in reality, birds would suffer food poisoning from chocolate and die.
Pixar's third film to show blood: Carl hitting the construction worker with his cane and blood seeping through Kevin's bandage. The first two are Finding Nemo and The Incredibles.
On the DVD cover, the dogs fly Curtiss F9C-2 Sparrowhawk fighter planes. In the 1930s, the U.S. Navy's Akron and Macon airships were designed to carry these aircraft; the trapeze system for launching and recovering them worked, but both airships were lost in storms.
The married life sequence begins at 7:15 of the film and lasts about 4 minutes.
The orange and white leaf blower Russell uses is modeled on the Stihl BG-50.
The first Pixar film presented in a 1.85:1 aspect ratio since Finding Nemo.
The first Pixar film since The Incredibles to feature the Luxo Jr. ball; the ball had appeared only in the short film Jack Jack Attack and in the alternate opening. Up is the first feature film since Nemo to feature the ball.
This is a rare example of a Disney/Pixar film showing graphic violence: Carl hitting the construction worker with his cane and Muntz falling to his death.
The film's official website has a video clip titled 'Ditch 'Em'; in the film the same scene plays with music, while the clip on the site has only sounds and effects.
Carl and Russell set off toward Paradise Falls, where extinct creatures live cut off from society. This journey takes place in a world surrounded by cliffs, just like in the 1925 film 'The Lost World.'
So was Paradise Falls inspired by Angel Falls in Venezuela? In fact, the landscape was modeled on Mount Roraima on the border of Venezuela, Brazil and Guyana. With its sheer walls and flat top (known as tepuis), this mountain looks as if it sprang from another planet. 'The Lost World' was also inspired by similar tepui landscapes.