Trivia

Gary Oldman, who played Sirius Black in the film series, expressed interest in playing Dumbledore.

After an open casting call for the roles of Harry, Ron, and Hermione, the crew received over 32,000 audition tapes, and reviewed between 500 and 1,000 auditions per day.

In an interview with the Independent, Jared Harris was asked if he would be interested in playing Dumbledore, the role originated by his father Richard Harris in the first two Harry Potter films. The junior Harris responded, "I mean, why do it? I don't understand. The films were fantastic - leave them alone." However, he did acknowledge that there was still "a lot of storytelling" from the books that the films omitted.

In the Shaun of the Dead commentary in 2005, Nick Frost... now cast as Hagrid... jokes that he's the new Robbie Coltrane, and that he'd play a drug-dealing Hagrid.

This is the second time that John Lithgow has shared a role with Sir Michael Gambon. They previously played Sir Winston Churchill in Churchill's Secret (2016) and The Crown (2016). The latter featured Harry Potter cast members Helena Bonham Carter and Imelda Staunton, as well as Jared Harris, son of original Dumbledore actor Richard Harris. This makes Lithgow the seventh actor from the series to have played Churchill. The others are: David Ryall (in Le grand Charles (2006)), Brendan Gleeson (Au coeur de la tempête (2009)), Timothy Spall (Le Discours d'un roi (2010)), Gary Oldman (Les Heures sombres (2017)), and Robert Hardy (Winston Churchill (1981)). Lithgow shares another role with Hardy, as they have both played Franklin Delano Roosevelt, in Winston Churchill (1981) and Les Géants de guerre (1994).