Wired has posted a new article where they reveal 13 facts about Harry Potter filming. They also have some bonus information about animals that is rather amusing:

[…] when costumed as Hagrid, Robbie Coltrane has managed to get both a fruit bat and a mini-fan caught in his half-giant beard. The latter was cut out, although we never found out what happened to the bat…

More fortunate were the 40 kittens who were filmed to appear on the moving plates in Professor Umbridge’s chintz-tastic office. After they’d performed their starring roles, they went on to be domestic pets with their new owners unaware of their Hollywood backgrounds.

• One of the first ever sets created for the Harry Potter films, the Great Hall is, as the name would suggest, pretty huge. It could fit 22 double-decker buses in and took over 90 tonnes of plaster to complete, as well as the handiwork of 30 men over 18 weeks. The tables and benches were made specifically for the film. The tables stretch a whopping 121 metres, with double that from the benches. Over the past seven years, the actors have added their own graffiti to the furniture — much encouraged by set designer Stuart Craig!
• Every wand seen in any of the Harry Potter franchise has been created on-site — including the 60 to 70 Daniel Radcliffe has worn out during the last seven films. Just like in the books, no two wands are alike, not even those of identical twins Fred and George Weasley. Although Radcliffe has been through a few, most of the wands have remained the same throughout the films, staying he same throughout the films, staying a consistent 13-15 inches (33-38 cm) long, like in the books. This means the characters have grown into their wands over years of filming. Dumbledore’s wand has also stayed the same, although its elaborate design was imagined before the film company — or the rest of the world — knew of its significance as the Elder Wand.
• Over 600 school uniforms have been created for Harry Potter. The battle scenes in Harry Potter and the Deathly Hallows have been the ones with the largest number of cast and extras to dress — the finale saw 400 Death Eaters and Snatchers join 400 teachers and Hogwarts pupils in the Great Hall.
• The Hogwarts Express is actually somewhat of a misnomer. In railway speak, the name of the train which makes the ritual journeys to school every September 1 is the ‘Hogwarts Castle’. The Hogwarts Express is the name of the service route. The train engine measures just under 4 metres high and 2.7 metres wide, was built in 1937 and was brought in from Carnforth in Cumbria. There are four carriages which date back to the 1950s attached.
• Pictured are just some of the 210,000 coins made for the Gringotts bank scene in the final two films alone. Other one-of-a-kind artefacts in the book which have been recreated on screen include Salazar Slytherin’s locket, of which 40 versions were made to accomodate Harry and Ron’s attempts to destroy it.
• Harry Potter’s identifying scar has been applied by makeup teams an approximate 5,800 times. While Radcliffe makes up a meaty 2,000 times of that application, the rest have been on the foreheads of stunt doubles and film doubles, who all wear the scar. Although Radcliffe’s favourite prop is his glasses, he has been through 160 pairs of them during the shooting of the franchise!, many of which do not feature glass as this reflected the cameras too often.
• Over 25,000 items of clothing have been used in the Harry Potter franchise.
• The pub owned by Dumbledore’s brother Aberforth in the village of Hogsmeade is home to another animatronic in the film. The hog’s head inside the tavern is a full-size silicon-skinned animatronic which was operated through the wall by technicians. Created as an alternative to three computer-generated wolf heads, which director David Yates originally wanted, the hog’s head took a month to complete. Every hair on it has been individually punched in by hand
• 200 mythical creatures have been created for the Harry Potter film series, including this dragon. Aragog the acromantula (giant spider) which featured in the second film, Harry Potter and the Chamber of Secrets, had a leg span of 5.48 metres. 250 non-robotic animals have been used in the films, the largest being a hippo and the smallest a centipede.
• Bill and Fleur’s home, where Harry, Ron and Hermione shelter in the final film, was 90 percent completed at Leavesden studios and then moved to Fresh Water West in Wales. It was transported by a tractor along the beach before being carried up the dunes by the crew. It’s public location makes it the most photographed set by fans. 4,500 individual giant scallop shells were needed for the roof of the cottage, and even the surrounding dunes were not except from Hollywood styling: hundreds of tufts of grass were individually dressed into the sand. The set resisted the coastal winds thanks to over 10.9 tonnes of water used to weigh it down.
• This [the boathouse] is just one of the 588 sets which have been created for the Harry Potter films — the products of 58 full time art department staff. Many of the sets have been created in the old aerodrome-turned-magic land that is Leavesden Studios. The 80 hectare studio houses over a 46,500 square metres of stages. The sets on them include a broom rig for flying — the brooms in the Harry Potter films are made out of aircraft-grade titanium.
• While these are the transfigured army of statues to fight against Voldemort at Hogwarts, they are not the only characters who wear masks in the film. Indeed, it is the masks of the Death Eaters which demanded most skill from the crew. Created in conjunction with the art department and the prop makers, all the Death Eater masks were sculpted by the creature effects department from a cold alginate life cast of the actors’ faces which took 2.5 minutes to set. The prop team then finished these to create an individual pewter design.
• This scene [Ron and Hermione in battle wreckage] showcases just some of the 5 29-tonne trucks’ worth of polystyrene rubble used in the Deathly Hallows films.

Thanks TLC!