1.When Voldemort died in the Battle of Hogwarts, he was 71 years old.
2.The number that Arthur Weasley enters in the phone booth to get to the Ministry of Magic with Harry is 6-2-4-4-2. The letters underneath those numbers on a standard telephone keypad spell out "magic."
3.Quidditch is the most popular sport among witches and wizards only in Europe. In America, however, the game Quodpot is preferred.
4.Track 7½ in King's Cross Station is the departure point for a long-distance train that stops at all wizard-only European villages.
5.Professor Snape is based in large part on J.K. Rowling's old chemistry teacher.
6.After Hogwarts, Hermione worked for the Ministry of Magic in the Department for the Regulation and Control of Magical Creatures to gain more rights for house elves and other magical creatures. Later she switched to the Department of Magical Law Enforcement.
7.Harry and Ron both became Aurors and completely changed the department.
8.Harry quickly became head of the Auror Department and then later of the entire Department of Magical Law Enforcement. He also gave occasional lectures on Defense Against the Dark Arts at Hogwarts.
9.Ron later left his job in the ministry and joined his brother George in managing the increasingly successful Weasley's Wizard Wheezes.
10.After Hogwarts, Ginny Weasley became a professional Quidditch player. When she later had her first son with Harry, she joined the sports editorial staff of the Daily Prophet.
11.Harry and Ginny named their children after Harry's parents, Lily and James, as well as Albus Dumbledore, Sirius Black, Severus Snape, and Luna Lovegood.
12.George Weasley married Angelina Johnson. Together, they have two children: Fred and Roxanne.
21.After Hogwarts, Luna Lovegood became a naturalist and during her work met Rolf Scamander, whom she later married. Rolf Scamander's grandfather is Newt Scamander, the hero of the film Fantastic Beasts and Where to Find Them.
22.After getting married, Neville Longbottom and Hannah Abbott moved to London. Neville worked for a short time as an Auror, but then became a teacher of Herbology at Hogwarts. Hannah, as the new innkeeper, ran the Leaky Cauldron, where the couple also lived together.
23.Rowling modeled the young Hermione more or less on herself. She even gave her her own favorite animal as a Patronus: an otter.
24.If it had been up to his father, Draco Malfoy would have gone to school at the Durmstrang Institute. However, his mother did not want to send him so far away.
25.J.K. Rowling used her depression following the death of her mother as the model for the Dementors and the feeling that they trigger in you.
26.Harry, Ron, and Hermione were sent to school in 1991.
27.In Harry Potter and the Goblet of Fire, there is a scene in Dumbledore's office in which there is a clear allusion to the Deathly Hallows, along with a winking dialogue.
28.Before the filming of Harry Potter and the Prisoner of Azkaban, director Alfonso Cuarón had his three main actors write an essay about their characters. Emma Watson wrote 16 pages about Hermione, Daniel Radcliffe wrote a page about Harry, and Rupert Grint never delivered even a single sentence.
29.In the closing credits of the same movie, there is an easy-to-spot love scene. Below on the left:
30.Tom Felton first read for the parts of Harry and Ron, but was finally cast as Draco Malfoy.
31.During the filming of Harry Potter and the Prisoner of Azkaban, the pockets of Tom Felton's Hogwarts cloak were sewn shut, because he kept trying to smuggle food onto the set.
32.When the Horcrux kissing scene with Harry and Hermione was filmed, Rupert Grint had to be sent off the set, because he couldn't stop giggling.
33.In the churchyard of Greyfriars Kirk in Edinburgh, there are three gravestones with the names Thomas Riddle, William McGonagall, and Elizabeth Moodie, which are said to have served J.K. Rowling as the basis for her characters' names.
34.Because readers of the books had problems pronouncing Hermione's name, Rowling wrote a scene in which she explained her name to Viktor Krum.
35.J.K. Rowling rejected a request from Michael Jackson, who wanted to produce a Harry Potter musical with her.
36.Professor Dumbledore has a scar over his left knee which is in the shape of the London Underground map.
37.For a long time, it was J.K. Rowling's plan to end the final Potter book with the word "scar." When writing it, however, she decided to go with "All was well."