Continuity mistake: When they escape from the building in the first dream, the right-hand mirror of the van is broken by the narrow gate. In the following shot when they are driving, the other mirror is broken and the right mirror is suddenly undamaged.
Revealing mistake: When Ariadne is pulling the two huge mirrors close together underneath the bridge with Cobb, watch her when she is closing the second mirror. She steps over something even though there is nothing present for her to step over. There must have been a green screen frame there for her to step over.
Continuity mistake: At the beginning of the movie, when Cobb and Arthur are on the top of the building about to get into a helicopter to leave, they find Saito in their helicopter. During the dialogue between Saito and Cobb, the window of the helicopter behind Saito is wet and being rained on. But when the camera cuts to Cobb outside the helicopter, it is not raining at all. This happens multiple times in the scene. As the helicopter flies away at the end of the scene, there is no rain.
Deliberate mistake: During the mob scene outside Saito's love nest, the same black Saab is seen getting firebombed twice. It was shot from two different angles, with the two shots played about a minute apart to give the impression of two cars getting bombed. Also, in the first angle it is clear the car has no engine.
Continuity mistake: In the scene where Ariadne finds out that the only way Cobb can dream is by being hooked up to the machine. When she first walks in and sees him sleeping on the chair she has a purse over her left arm. But in the next shot, she has no purse on either shoulder and there's no shot showing her putting the purse down.
Deliberate mistake: The exact same filmed footage of sleeping Arthur is shown in two different scenes inside the van. This repeated slow-motion scene shows his left hand rising and two spherical droplets of water drift towards his right eye. It can be first seen when the van is being chased out of an alley and makes a right turn onto a street. Then it can be seen again soon after the motorcycle rider smashes into the windscreen. Watch for it when the van passes through open gates and makes a right turn.
Continuity mistake: In the second layer of the dream, when Ariadne and Arthur are sitting together, Ariadne's hair changes between shots. At some times, her updo is tied on top of her head, and sometimes, it is a bun at the back. It looks as if the hair is completely opened and tied again in a different way between shots. It must be because of the shots being recorded at different times.
Continuity mistake: When the train comes barreling down the street in the level 1 dream (on the plane) in the rain, the length changes. In an overhead shot we can see what appears to be three cars (including engine). It is moving quite quickly and should pass them in no time, but Cobb has to back around the train and catch up. It appears as he is backing around that more than three train cars have passed.
Continuity mistake: During the shifting gravity scene in the hotel room, Arthur rolls off the bed, catches the gun, and shoots the projection. As they slide towards the door, Arthur is curled up and facing away from the projection. But in the next shot, when we see them close up, Arthur is facing toward the projection and is no longer curled up.
Continuity mistake: In the beginning, after Nash dumps Cobb into the tub, Saito grabs Nash from behind, hits him, and then turns around and points his gun at Arthur. Nash is dry. But, in the next shot, Cobb jumps out of the tub and wrestles Saito to the ground. Before Cobb grabs Saito, it is shown that Nash is now soaked.
Continuity mistake: As Cobb is finishing describing how powerful a dream is, his right arm hangs down out of sight as his left thumb touches his forehead, then drops to rest on the table. A wine glass stands to his left. When the viewing angle reverses, his left arm is instantly hanging so that the hand is in his lap, and his right hand is bringing the wine glass to his mouth, yet the conversation is real-time continuous.
Continuity mistake: Just before the shifting gravity, Arthur walks out of the room and begins walking down the hallway. As we see him from behind, the elevator door opens and a projection is revealed. But, when the elevator doors are opening, Arthur slows down and just before we see him from the front view shot, his bead begins to tilt down. Then in the front view shot, he slows and tilts his head down again to avoid the projections contact.
Factual error: When Cobb arrives at Los Angeles International Airport and is going through immigration, the officer stamps his passport with a black stamp. All passport stamps in the United States are universally the same with a blue oval and pink letters marking the date in the center. Plus the fact that US citizens don't get their passports stamped when they return to the country.