Goofs

• Continuity: When Harry breaks his right arm playing Quidditch, he takes great care to keep it held up as he rolls from side to side to avoid the bludger, but at one point he puts his weight on it without any apparent discomfort. In the next shot he is holding it across his stomach again.
• Revealing mistakes: When Harry and Hagrid hug (when Hagrid has just returned from Azkaban), the flames in the bowls hanging on the wall behind them burn backward briefly. This occurred because (according to Emma Watson in an interview on the Prisoner of Azkaban DVD) the filmmakers paused this shot. This was because Emma was so embarrassed to hug Daniel in front of everyone, they had to stretch, or replay a portion of the shot to get the right length of footage.
• Revealing mistakes: During the Quidditch match, the wire that attaches the broom to Harry is visible for several seconds.
• Incorrectly regarded as goofs: The students are able to carry on conversations and hear instructions while wearing the earmuffs that protect them from the screams of the mandrake roots. We assume the earmuffs to be enchanted to specifically block mandrake screams, but not other sounds. Despite what "it says in the book" there is nothing in the movie to suggest that this could not be the case.
• Continuity: Ron receives the "Howler" from his mother. After his owl, Errol, crashes into the table, you can see that the red envelope is open. As Ron removes it from Errol's mouth. We then see Ron breaking the seal on this envelope so he can read it.
• Continuity: When Harry and Ron's car is caught by the tree, a limb smashes a hole in the rear window but the hole is missing in one shot when the car tips forward while falling out of the tree.
• Incorrectly regarded as goofs: At the beginning of the transfiguration lesson, the writing on the blackboard behind Professor McGonagall is reversed, and this has been reported as a flipped shot. However, further observation reveals that the right-hand board is, for undisclosed wizardy reasons, a mirror image of the left-hand board and so this is not an error.
• Continuity: When Harry and Ron are in the Dark Forest and the spiders begin to attack, Hagrid's dog gets in the car twice.
• Revealing mistakes: When Ron is on all fours beginning to cough up slugs, Harry says, "Let's take him to Hagrid's." Hermione mouths the lines with him.
• Continuity: At all times the Locomotive 'Hogwarts Castle' is played by a Great Western Railway Hall Class Locomotive. However, when Harry and Ron are in the car and look behind them to see the train bearing down on them the front of the engine is quite different, although the numberplate and nameboard are the same.

Taglines

• "Dobby Has Come To Warn You Sir."
• Hogwarts is back in session.
• The Chamber of Secrets has been opened. Enemies of the heir... beware!
• Something Evil Has Returned To Hogwarts!
• The Chamber of Secrets has opened...
• The second year begins November 15

Trivias

• Daniel Radcliffe has said that "Harry Potter and the Chamber of Secrets" is his favorite book.
• Hugh Grant was originally cast as Gilderoy Lockhart but was forced to withdraw at the last moment because of scheduling conflicts. Alan Cumming was also considered.
• Zoë Wanamaker does not appear in this film as Hogwarts' flying instructor, Madam Hooch. Her character was written out.
• Christian Coulson landed the role as Tom Riddle, even though he was 23 and exceeded the 15-17 age group set for auditions.
• Fourteen Ford Anglias were destroyed to create the scene where Harry and Ron crash into the Womping Willow.
• The "Let's just hope Mr. Potter will always be around to save the day" dialogue (see quotes) was improvised by Daniel Radcliffe and Jason Isaacs.
• During the shoot, the part of Dobby was played by a ball on a stick (he was added digitally later, of course).
• The train station interior used in the film is Kings Cross in North London, whereas the exterior shot is actually St Pancras. The two stations are adjacent to one another, but not the same building. This was done because the architecture of St Pancras is much more visually appealing.
• As Harry enters Professor Dumbledore's study, a portrait of Gandalf the Grey is included in the collection of the great wizard paintings. It is above the door-frame and slightly to Harry's right.
• Filming began three days after the release of Harry Potter and the Sorcerer's Stone (2001).