Harry Potter & The Deathly Hallows' Two-Way Mirror Plot Hole
The two-way mirror shard from Harry Potter and the Deathly Hallows was one plot hole that left fans of the movies unfamiliar with J.K. Rowling’s book series scratching their heads. The Harry Potter novels are known for their meticulous continuity. Considering how much content had to be cut for the films, the screen adaptations are strong interpretations of the novels. However, the movie's explanation behind a magical two-way mirror shard that Harry carried throughout The Deathly Hallows Part 1 and Part 2 was glossed over, although it turned out to be a life-saving plot device.
In Harry Potter and the Deathly Hallows, Harry had a small shard of mirror in which he began to see flashes of who he thought was Albus Dumbledore. When Harry and his friends were trapped in Malfoy Manor, Harry used the shard to call for help, and Dobby appeared. In The Deathly Hallows Part 2, they discovered that Dumbledore’s brother, Aberforth, had the rest of the mirror. Aberforth admitted that he got it from Sirius Black’s house via Mundungus Fletcher and had been keeping an eye on Harry on his journey to find Voldemort’s Horcruxes.
However, the presence of the mirror, as well as why Harry had a shard of it, how Harry (Daniel Radcliffe) knew that it used to belong to Sirius Black, and how Aberforth knew that he could use it to monitor Harry’s safety were all left unexplained by the films. This magical item was only vaguely explained in The Deathly Hallows movies because it wasn’t introduced in Harry Potter and the Order of the Phoenix. The movie's omission of a seemingly insignificant detail from the novel where Sirius gave Harry a two-way mirror that would allow them to converse while Harry was at Hogwarts left a significant hole in the usually meticulous storytelling of the Harry Potter universe.
In the novel version of The Order of the Phoenix, the pair of two-way mirrors were more important plot devices, and their introduction to the series early on better prepared their later roles in The Deathly Hallows. The two-way mirror set that Sirius Black gave Harry was not used in the novel, so the scene was cut out of the film version. However, the fact that the mirrors were not used turned out to be a plot device in and of itself. Harry had decided not to use Sirius’s gift, thinking that he might only get his reckless godfather in more trouble. Harry only remembered his mirror at the end of Order of the Phoenix, after the events of the Department of Mysteries and Sirius’s death. Harry broke his mirror once he realized that Sirius might still be alive if he had used it to check on him before going to the Department of Mysteries at the Ministry of Magic instead of relying on Floo Powder. A single shard of the broken mirror found its way into Harry’s school truck, which he happened upon years later during the events of The Deathly Hallows.
Leaving the mirrors out of The Order of the Phoenix movie seemed like a harmless omission at the time. It is a testament to Rowling’s intricate planning that such inconsequential objects could become so important two novels later. First-time audiences focused on the action of the final Harry Potter film will not necessarily question the sequence of events that only occur because of the presence of the unexplained magical object. However, the near exclusion of the two-way mirror was confusing for fans of the Harry Potter and the Deathly Hallows and other Harry Potter movies who have never read the books. The full explanation was left out of the movies, and the impact of the mirror and its emotional connection to Sirius was much more intricate in the novels.