1. The graphics team has written thousands of letters, but then discovered that they were too heavy for the owls, so they had to write it again. Even then they took six months to teach the owls do carry mail.
2. Wing doors in Gringotts was actually works. It took three months to make the basement door at Bellatrix act as what we see on film.
3. More than 20,000 of goods in the windows at Diagon Alley. And they are handmade.
4. Daniel Radcliffe, Rupert Grint and Emma Watson have not seen the Great Hall until they filmed the Sorting Hat so that feelings of shock and fear in the film is absolutely real.
5. Only one staircase was built for the film. The rest is multiplied by digital.
6. Beard Hagrid was made from six different hair pieces. And there are many things that have been stuck in that time, including bats.