Continuity mistake: When the robots invade New York City and are advancing on Polly in the street, the camera pans down to the robots' stomping feet. There is nothing there but open space for them to tromp on. The camera pans back to Polly taking a picture, then back to the robots' feet. Suddenly, a car has magically appeared in the path of the stomping robots and gets kicked towards her. (00:12:15)
Factual error: After the robots first attack New York City, a series of newspapers is shown. The German one is full of mistakes. It says "Sehr grosse metallic Maschinen stehlen stehlen Reserven." The word 'metallic' would be 'metallisch' in German and they would write robots as 'roboter'. 'Stehlen' (steal) is written twice. (00:15:15)
Character mistake: After the robots first attack New York City, a series of newspapers is shown. One of the headlines in the French one reads "La Tour Eiffeil est détruite". The proper spelling is "Eiffel" (00:15:55)
Revealing mistake: On each of Sky Captain's hangar doors, the windows are broken in the exact same places, indicating the same window rendering was simply duplicated to make the others. (00:16:45)
Factual error: When Dex first tests his ray gun, the reflection in his glasses goes in the wrong direction. (00:17:30)
Continuity mistake: In front of Totenkopf's office, Joe shoots the robot with the metal melting gun, then push it on the ground. When the robot falls, it breaks the electric device that killed the scientist but in each following shot, the device is not broken. (01:23:15)
Continuity mistake: A montage scene of newspaper headlines early on has March 12, 1939 as the date. Much later in the film, Jude Law asks Gwyneth Paltrow the date so he can calculate the position of a star. She responds "March 2" but there is absolutely nothing to indicate that nearly a year has passed.
Continuity mistake: When Joseph and Polly enter the Ark, we see the door close behind them, the countdown coming to zero. The Mysterious Woman, at the time, is out cold, or at least a dozen meters behind them. Yet, she finds her way onboard the Ark somehow.
Deliberate mistake: Polly's and Sky Captain's clothes are discarded because they are contaminated with uranium; however, Polly gets to keep her camera. Her camera would have been contaminated with uranium, too, because she had it with her in the underground cave.
Revealing mistake: When the robots breaks the walls of the room where Dex is, there is a lot of debris that fall on the floor. A big piece of debris in the middle of the screen passes through another.
Factual error: At the very end, Polly Perkins takes a spectacular picture, using the very last shot on her only roll of film. When Sky Captain tells her she left the lens cap on, she is mortified. But she would certainly know that on her Argus 35mm camera, all she had to do was remove the lens cap and retake the shot. Unlike modern idiot-proof cameras, hers has no mechanism to prevent double-exposures.
Continuity mistake: When Polly stands up while Joe is attacking the robots, she is on the corner of a sidewalk. A few shots later, when Joe flies over her and she says "Joe", she is at a different place on the sidewalk. She was walking really slowly, so it's impossible that she moved that fast.
Factual error: Polly Perkins takes a flash picture in the radiation-contaminated mine in Nepal. But her camera has no flash attachment.
Continuity mistake: When the robots are going to capture Dex, the amount of debris and papers around him changes in each shot.
Other mistake: When Polly notices the reflection of Joe's airplane marking on the water, the code "hllod" gives "Polly." That's impossible. To get "polly" from "hllod," a person would have to rotate the word 180 degrees, not view it as a mirror reflection.
Deliberate mistake: Just before Sky Captain goes to the rocket ship he punches Polly in the face hard enough to knock her out, and yet she has no swelling nor any type of bruise for the remainder of the movie. A punch that hard would have surely left at least some type of mark on her, especially with her being so fair-skinned. (Yes, this was deliberately done, hence a deliberate mistake.)
Continuity mistake: Polly meets Dr Jennings at the Radio City Music Hall at 6 pm but when she talks to Sky Captain later, she says that she met him in the morning.
Continuity mistake: On Totenkopf's rocket, Joe runs to cross the bridge, but Polly looks at the control panel behind her and pushes a button. Even if a few seconds have passed, Joe is still next to her.
Continuity mistake: When the scientist is killed by the electric device in front of Totenkopf's office, he is transformed in to ashes and bones but in the following shot, there are only bones on the floor.
Continuity mistake: On the airplane, Joe draws a line on the map to see where they will crash. The line changes place in each following shot.
Chosen answer: About 95% is CGI. The only real part of the movie was the actors themselves (and small objects they handle), with the exception of Dr. Totenkopf, portrayed using archive footage of Laurence Olivier. Everything else was CGI.
Guy