The films' protagonist trio Daniel Radcliffe, Rupert Grint, and Emma Watson appear throughout the special, along with surviving principal cast members Helena Bonham Carter, Robbie Coltrane, Ralph Fiennes, Jason Isaacs, Gary Oldman, Tom Felton, James Phelps, Oliver Phelps, Mark Williams, Bonnie Wright, Alfred Enoch, Ian Hart, Toby Jones, Matthew Lewis, and Evanna Lynch, producer David Heyman, and filmmakers Chris Columbus, Alfonso Cuarón, Mike Newell, and David Yates.

[4] J. K. Rowling—the author of the original Harry Potter book series, who had a significant role in the production of the film adaptations—is largely absent from the special.

Critics speculated that this was due to her views on transgender issues and, as The Daily Telegraph's Ed Power put it, consequent "public rebuke by the series' stars".

[5] However, Entertainment Weekly reported that Rowling had been invited to appear but she felt that the archival footage was sufficient, with "sources close to the situation" denying that the author's decision was related to the controversy surrounding her remarks on transgender issues.

The site's critical consensus reads, "Affectionate and revealing, Return to Hogwarts offers an intimate glimpse into how the making of the Harry Potter franchise delivered its own special kind of magic for those involved.