When the Phantom is on the rooftop after Christine and Raoul leave, you can see the Phantom's footsteps in the snow, but not Christine's and Raoul's.
When Meg steps out of the underground river and into the Phantom's lair, her brown pants are clearly soaked with water; a few moments later, when she finds the Phantom's mask in the bedchamber, her pants are perfectly dry.
Christine's hair is wild while running up the staris in "Why have you brought me here..." and then on the roof her hair is pulled back.
When Christine lights a candle for her father in the chapel after "Think of Me", she lights her match from another candle. However, when the shot switches to over her shoulder, the candle she lit is the only one burning.
During the Point of No Return scene, when the Phantom grasps Christine's wrists, the gold bracelet become unclasped. Yet when the camera view switches, the bracelet is secured and in place.
When the Phantom takes Christine down to the catacombs for the first time, her hair and makeup slowly change from being simple and understated, to more sophisticated and womanly. The director has stated that this was deliberate and that the change in Christine's appearance during this scene was intended as a metaphor to representing her sexual awakening.
When The Phantom brings Christine to the lair, she is wearing stockings. However once she faints and the scene shifts to the Joseph Buquet scene and then back to the lair, they are mysteriously missing. One explanation for this, however, is that the phantom simply took the liberty of removing Christine's stockings while she was unconscious.
In the beginning, where Raoul is riding his carriage to the Opera House, it looks as if there is a bag of bright blue Ruffles chips in the seat. However, if you look closely it is his family's coat of arms.
During Christine's first performance, once the audience appears, if you slow the video down, you can clearly see that the actors in the very back left of the theater are legless mannequins with cloth thrown over the tops.
During the chandelier scene, the crowd is running and you can see the knee pads on the women when their dresses come up.
When the Phantom is on the rooftop after Christine and Raoul leave, you see the Phantom's cape blowing in the wind. If you look closely, you can actually see that there are two capes blowing in the wind, one under the other. This is due to the fact that the film editors added a digitally created cape to blow in the background, but for whatever reason, did not match its movements with the real cape the Phantom was wearing.
After Raoul swims up to take his breath while trapped under the grate, the iron grid is shown dropping into the water. However, the bubbles travel downwards, showing that the shot was reversed.
The rope that the Phantom cuts and causes the chandelier to crash is hanging limp when it is tied to the rail on the stage, which means that when it was cut it would only probably hang there. If it really was the rope keeping the chandelier suspended then it would be taut because of the weight.
In the "Masquerade" sequence, as per the stage show, the chorus sings about all the colors of the masks and costumes on display ("Every face a different shade... Flash of mauve, splash of puce... Spinning yellows, grinning reds" (etc.)). Unlike the stage show, however, in the film all the masquers are wearing black and white.
In the opening scene, Madame Giry is Meg Giry, not her mother as has been stated by others. The elder Madame Giry would have to be deceased given her age during the movie and 49 years that have passed since those events. Meg, however, would have been around the same age as Christine, making her around 65 during the opening scene.
In a 1919 scene, a shop shows the Swarovski swan logo. At the time, Swarovski's logo was an edelweiss flower. The swan logo was adopted in 1988.
The screenplay says that the Masquerade ball takes place on New Year's Eve in 1870. Such a decadent party would have been highly unlikely at that time, given that Paris was under siege by the German military from September 1870 until late January 1871, and that food was extremely scarce.
The Phantom writes a song about the "Point of No Return." This phrase originated in the 20th century to describe the logistics of air travel.
The color of the stage lighting in most of the stage performance scenes is a bright, hot white. The source shown is gas which would be dimmer and a much more yellow color. Also, the shadows cast by the lights are sharp which would have been impossible from the gas lights.
When Raoul runs to Christine and says "Are you alright", we hear her say "Raoul we're not safe here" but her mouth does not move.
Throughout many songs in the movie, the actors' mouths are not matched up with the music.
During the singing of "Don Juan", La Carlotta is heard singing an ending note but you see her smiling and pointing and shoving, not singing at all.
At the end of "Music of the Night" as the Phantom is laying Christine into her bed, his mouth and the audio are unsynchronized.
During "Prima Donna" Carlotta's lips do not match the words being sung.
At some point during the "Music of the Night" scene, the shadow of a giant camera can be seen on the wall.
During the "Music of the Night" scene, right as the Phantom says, "Open up your mind, let your fantasies unwind," the shadow of a camera/camera rig can bee seen on Christine's face.
When Raoul is on his way down the stairs to the Phantom's lair, he falls through a hole, down into a pit of water. Iron bars then lower from above, but since Raoul fell straight down into the water, it would be impossible for the bars to be there.
Box Five is the Phantom's box, to be reserved for his usage. However, the Opera House depicted in the movie has only four boxes.
After Raoul and Madame Giry ascend from the trap door scene at the end of the masquerade ball, they proceed down a stone hallway and the boom mic is visible at the lower right corner of the screen.
During "Music of the Night", when the Phantom is carrying the fainted Christine towards the bed, Christine's head accidentally hits the large tassel on a nearby curtain.
The black, decorative baton used by the conductor is a presentation baton sometimes given to retiring maestros. It would never be used in performances as it was too heavy and, being black, would be too hard for the musicians to see in a gas-lit theatre.
When Raoul cheers Christine's debut, he calls out, "Bravo!" It should be "Brava!"