Harry Potter 20th Anniversary: Return to Hogwarts celebrated 20 years since the Wizarding World's first film.
Offering interviews with the magical trinity, we also heard stories from the gigantic alumni of actors. One of which involves a story where one cast member accidentally injured another on set.
Read More: Hogwarts Legacy: Everything You Need To Know
Harry Potter Actor Bruised Co-Star On Set
The incident occurred between Jason Isaacs and Tom Felton, both of whom portray father and son, Lucius Malfoy and Draco Malfoy respectively.
During the filming of Harry Potter and the Chamber of Secrets, there's a scene where Harry Potter is hiding in a case inside the Borgin & Burkes. The cross-headed wizard witnesses Lucius smack Draco's hand using his cane, but this left an actual, accidental mark on Felton's hand.

The segment is a deleted scene but Jason Isaacs does shed more light on the moment:
It sounds like it really hurt Tom Felton, but the young star was strong enough to carry on filming:

Tom Felton commended how Isaacs immediately apologised after the shot ended.
The Special episode is available on HBO Max (US) and NOW (UK). We also learned that one of the actors making up the Golden Trio was about to leave the franchise.