Continuity mistake: In the second scene, when Cobb is taken to Saito (Old Man), Cobb's totem is kept on the table with the longer end down. But as the PoV changes to Saito's, the totem keeps changing position with the shorter end down. This happens at least four times. (00:01:45)
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. (00:03:10)
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. (00:54:20)
Continuity mistake: In the scene on the airplane when they are setting up to go under, Yusuf takes a sip from a wine glass and goes to set it down. Then in the shot immediately following he no longer has a wine glass in his hand. Instead he is buckling his seat belt. (01:03:50)
Continuity mistake: During the vehicle chase in the first dream, the taxi's driver's side windows are shot out. In the next shot, while it is backing up and hitting another car, the windows are intact. And in the next shot, the windows are broken again. (01:04:30 - 01:06:00)
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. (01:06:05)
Continuity mistake: After the 1st-level shootout in the rainy streets, the two cars arrive at a warehouse. As they drive in, we see the wet tracks their tires left in previous takes of the same entry. (01:07:20)
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. (01:29:30 - 01:38:55)
Continuity mistake: When Arthur is fighting the projection in the hallway and begins to strangle him using the projections arm, we see his arm is covering his mouth.However in the next shot his arm is around his neck and his mouth is uncovered. (01:48:55)
Continuity mistake: When Ariadne wakes in the Snow Fortress and the floor goes from under her, we can see her gloves fall in to the crack but in a different camera shot of her we can see the gloves are now back near her head again. (02:12:20)
Continuity mistake: In the climax scene when Cobb embraces his children, in the first frame he lifts up Philipa, but a moment later in the next frame, we observe that its James now in his arms while Philippa clings on to his leg. (02:17:05)
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: 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.
Continuity mistake: In the hotel scene when Ariadne and Arthur are sitting watching Mr Charles walk in to talk to Fischer, we can see she has earrings, but later when Ariadne asks "wait, whose subconscious are we going into?" we can briefly see she has no earrings.
Continuity mistake: When Cobb and Arthur are leaving their hotel room to get on a helicopter on the roof, we can see it's quite dark outside. But in the shot of them on the roof, it's much brighter.
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.
Visible crew/equipment: During the zero-gravity fight scene in the hotel room, it is possible to see a crew member's hand briefly resting against the end of the bed when Arthur and the projection are fighting on it.
Continuity mistake: Third dream level, there are six henchmen being pulled by the Hummer snowmobile, and the back right gets shot off (or taken out). A scene a few minutes later, the missing henchman is back, then a few minutes later he is gone again.
Continuity mistake: As the van is in free-fall from the bridge to the water, Arthur's headphones disappear and then reappear between various shots.
Answer: The answer above is solid and I agree, but there's another plausible way of looking at it. It is implied at the end that Cobb could still be dreaming (we never see if the top stops spinning). If that's the case, then he would likely dream his children to be exactly how he remembers them.
jshy7979