The coaches of the train on which the Pevensie children travel have Great Western Railway colors and lettering. The engine, No. 7802 Bradley Manor, is painted and lettered for British Railways, which did not form until 1948, after the war ended.
The Pevensies observe blackout rules poorly. They have no blast tape on the windows, no blackout curtains, they open their curtains with the lights on, they leave lights on while they open the back door, etc. Then they are still in the house while the planes are going over. The war sirens went off when planes were spotted a couple of miles from the city itself, so the family should have had plenty of time to get out the house into the air raid shelter. Even though moments of terror make it hard to observe rules, it was precisely this terror that made Londoners obey the rules so strictly.
When Lucy pulls back the tree branches to enter Narnia for the first time, her hair is curled inward. When she feels the snow and looks around, her hair is curled outward. Then when she looks up, it is inward again.
When Susan goes to practice her bow Lucy joins her. Lucy then throws her knife at the target and hits the bullseye dead on. When the camera pans back to Lucy with a big grin on her face you can see her knife tucked safely away in its sheath.
Lucy got back her handkerchief from Mr. Beaver in the beginning, but it seems like Mr. Tumnus returns it to her again in the end, when they see Aslan walking away on the shore. However, it is likely that Tumnus is giving her his own handkerchief in the end, as the embroidery known to be on Lucy's is not seen.
When Lucy opens the wardrobe for the first time, three moth balls fall out. The camera backs off and you see all three of the moth balls stop in plain sight. Lucy turns around and then steps into the wardrobe. When the camera backs off again (showing Lucy closing the wardrobe door) the moth balls are gone.
When Lucy, Peter, Susan and the Beavers are just coming out of the tunnel, just before Lucy falls, her coat is on, then when she falls and they have a close up of her, her coat is off. When she is walking with Peter and Susan her coat is back on again.
In the opening scene when the Germans are bombing London, the
shot of the sky shows that it is very cloudy. However, when Peter and Edmund are running after retrieving the photo, the planes are clearly visible and are not masked by any clouds.
When Peter finds the note about the capture of Mr. Tumnus, he pulls it down off the nail, ripping the top edge of the paper. In a following shot the top edge of the paper can be seen fully intact, then ripped again.
When Lucy first enters Narnia and meets Mr. Tumnus she hides behind the lamp. When she comes out from behind it she has snow up the front of her dress to her waist, in the next shot she only has snow at the hem of her dress.
When Edmund is eating Turkish Delights after meeting the White Witch, the food changes hands (right-left-right) several times, and the powdered sugar on his clothing and mouth change position between shots.
At the beginning of the battle, Jadis appears from behind the hill with all her troops, stopping close to an upper natural "step" in front of her. Later, she orders her bears to move, but we don't see her falling - the step is gone.
When the children are in the tunnel underneath the Beavers' house, Peter is carrying a torch and Susan is carrying a lantern. However, when they emerge from the tunnel, neither the lantern nor the torch is in sight.
During Hide & Seek, Lucy tries a door at the end of the hallway, but it's locked. She tries the door to the right about five steps away, and it opens into the spare room with the wardrobe, but the entire left wall has windows; this would not have been possible if there were a room on the other side of the wall. In fact, there is a window to Lucy's immediate left upon entering (with the short cut of the buzzing fly). The only way this would have been possible within the layout of the house is if the locked door in the hallway was to a very shallow closet.
When Lucy first enters the wardrobe, you can hear Peter's voice reach a hundred after counting, but when she steps out of the wardrobe after her first visit to Narnia, you can hear Peter still counting up to a hundred.
After the climactic battle, as Aslan approaches Susan, Edmund, Peter, and Lucy; he stops, looks to his right, and breathes on a frozen figure. In the next shot from his rear where we can see the children, Aslan is looking to his left and there is nothing to his right.
After the four children get off the train, a motor car passes them by, leaving tracks on the muddy road. When Mrs. Macready drives up a few moments later with the horse-drawn cart, the motor car tracks have vanished.
In the beginning, when the German airplanes are bombing London
and Edmund and Peter are in the garden in front of their house, you can see the shadows of the airplanes on the ground. This is not possible because it is night and there is no light above the airplanes that could cause those shadows. On the contrary, searchlights tried to discover those airplanes from below pointing into the sky. If there was a light above the airplanes strong enough to create shadows, they would be moving much faster.
In the railway station, the train is stationary in several shots when it is supposed to be moving. The doors are alternately open and closed in these same shots. In some shots, the train's billowing smoke column disappears entirely. At one point just before the children get on (and we see the caption: directed by Andrew Adamson), the train simply vanishes for a short time during the shot overlooking the station.
When Lucy reaches the upstairs hall of the house and is looking for a hiding place, she tries the first door, which is locked. The second door is unlocked and she enters the room. The problem is that the room has windows on both walls. This would be impossible if the first door really led to a room.
There is almost no instance in the movie where we see the faintest bit of blood on the swords despite them causing many deaths. Even when Aslan asks Peter to clean his sword, it is as clean as ever despite having just impaled a fox.
The goof items below may give away important plot points.
During the coronation scene after they have all been crowned they sit down on their thrones. Afterwards there is a zoom in on all of their faces, but when they zoom in on Peter's face he is clearly still standing in front of his throne not sitting in it.
After Peter and Susan climb off the iceberg and discover Lucy is missing, Peter does not take his sword out of the iceberg. When Lucy rejoins them, you can see the iceberg with Peter's sword in it floating next to the bank they are on. When they move on, Peter still does not take his sword from the iceberg. However, in the next scene, he is seen sheathing it.
In the final battle with the Witch, Jadis first stabs Peter through the middle of his sword arm and the grass is green. When the shot is cut back to Peter and Jadis, the sword is only going through the chain mail on the upper part of his arm and the grass is brown.
When Lucy and Susan are playing in the water, they are barefoot. They get out and the wolf surprises them, they run up a tree, they are wearing sandals. After Peter kills the wolf, but he is still laying under it, the girls jump out of the tree barefooted again.
When Peter is fighting the Witch and turns around to see Aslan, he has a cut on his right side of his face, above his eye. The blood had run down past his eye. When Lucy heals Edmund the blood trickle is smaller.
When Susan, Lucy and Peter find Edmund lying on the ground (after the battle), Susan is sitting to the side to Edmund's head and proceeds to take off his helmet. In the next shot, Edmund's head is resting on Susan's knee.
During the coronation, Mr. Tumnus places a crown on Lucy's head. The front of the crown rests about 1 inch from her hairline. (Where her hair meets her forehead.) As the shots go back and forth between Lucy and Tumnus the crown gets closer to the hairline, resting just above her forehead and back again.
Near the end of the movie, Lucy gives Edmund the potion that is able to heal any wound. His major injuries are healed, but the cuts on his lip and face remain. When Santa gave Lucy the potion, he told her that putting the potion on any wound would heal it. When she gave the potion to Edmund she gave it orally, so it would heal his internal wounds.