- Alfonso Cuaron asked Emma Watson, Rupert Grint, and Daniel Radcliff to write an essay about their character. Emma Watson wrote sixteen pages, Rupert Grint wrote nothing and Daniel Radcliff wrote one page.
- Alfonso Cuaron asked the students to wear the uniform as their parents weren’t there. It is different from the previous series.
- Alan Rickman and Richael Harris put on a prank on Daniel Radcliff. They put a fart machine in Daniel Radcliff’s sleep bag.
- When Gary Oldman appears, (or Sirius Black) the shooting method is a reference to his previous movie.
- Newt Scamander made a cameo on the marauder’s map.
- In The Leaky Cauldron, a wizard is reading Steven Hawking’s book “The Brief History of Time”.
- There’s a portrait of Voldemort on the wall.
- Also, the portrait of Anne Boleyn, since she was accused of being a witch at her time.
- The marauder’s map misspelled “Mooney” instead of “Moony”, it is a nod to the visual effects supervisor, Karl Mooney.
- In the credit roll, there are two pairs of footsteps in the style of Marauder’s map.
- Buckbeak poops in the scene where Harry Potter is about to ride him.
- You can see Marge Dursley being a balloon in the sky while Harry Potter is leaving Privet Drive.
- Remus Lupin’s office is originally Albus Dumbledore’s office in the previous films.
- Remus Lupin was tired on the Hogwarts Express because the day before was a full mon – he was exhausted by the werewolf transformation.
- There was an eage eating snake in the scene of Hogsmede, which Alfonso Cuaron was paying tribute to his home country.
- Draco Malfoy used his broken hand to shove Neville away, indicating his injury was fake.
- The bartender made a bottle disappear.
