Tom Felton forgot his line when Draco sees Harry disguised as Goyle, so he improvised "I didn't know you could read".
It was Jason Isaacs' idea for Lucius Malfoy to have long, blond hair, as well as carry a walking stick inside of which he would conceal his wand. He grew attached to the stick, and once tried to take it off set before he was caught.
Shirley Henderson (Moaning Myrtle) is the oldest actress (age thirty-seven) to portray a Hogwarts student.
Daniel Radcliffe was initially only offered £125,000 (approximately $181,500) for this movie. The actors' union Equity stepped in and negotiated new terms, which increased his salary to roughly £2 million ($3 million).
The final Harry Potter film to feature Richard Harris as Hogwarts Headmaster Professor Albus Dumbledore. Harris died of Hodgkin's disease a few weeks before this movie's American release. Both Chamber of Secrets and its sequel Harry Potter and the Prisoner of Azkaban (2004) are dedicated to his memory.
Adrian Rawlins, Geraldine Somerville, Saunders Triplets: At the beginning of the movie, Harry is looking through the photo album he'd received from Hagrid at the end of Harry Potter and the Sorcerer's Stone (2001). The first photo he sees is of his parents, James and Lily, holding Baby Harry. None of the returning cameo actors were credited.
Chris Columbus: [children] All four of Columbus' children appear in this movie. Eleanor Columbus reprises her role of Susan Bones from Harry Potter and the Sorcerer's Stone (2001), Brendan Columbus plays a boy in the study hall, Violet Columbus plays the little girl with flowers, and Isabella Columbus plays the little girl in the bookstore.
Chris Columbus: [Christmas] When Columbus scripted Young Sherlock Holmes (1985), Watson believed Holmes obsessed over a case, because unlike other boys his age, even at Christmas, he had no family to go home to, like Harry Potter or Home Alone (1990)'s Kevin McCallister.