Continuity mistake: Back at the KAOS Headquarters when Siegfried finishes with the phone call he turns around to speak to the big man. The violin jumps from under his right arm to him holding it in his left hand.
Continuity mistake: When Max and 99 are fighting Dalip on top of the bakery, Dalip punches a hole in the wall beside 99's head. When he body slams Max, the hole has disappeared.
Continuity mistake: In the plane's bathroom, Max shoots himself several times with the mini-crossbow: in the cheek, ear, etc. After landing on the ground, all traces of the dart punctures are gone.
Deliberate mistake: When Max and 99 are in the air, they can be seen talking to each other. This is not possible (as proven on MYTHBUSTERS) even if you were yelling at the top of your lungs. The wind would make any noise unrecognizable, yet we hear them talking to each other just fine.
Continuity mistake: The Chief flies in a fixed undercarriage Cessna aircraft. During some of the flying sequences, the aircraft is shown as a tail-dragger with retracted undercarriage.
Factual error: When Max falls out of the trap door in the airplane, they show an overhead view of him falling, shot from the ceiling of the bathroom. You see his body falling briefly before they cut the camera angle. With the speed of a commercial airliner being in excess of 500 miles per hour his body would have left the camera's view within a split second of him hitting the outside wind currents.
Factual error: In the beginning of the film, Max is walking down the National Mall listening to his iPod. He walks toward the Smithsonian Building (the supposed location of CONTROL's headquarters). However, in the next shot, he is entering the National Museum of Natural History, which is on the other side of the Mall and is further down. Also, exhibitions of CONTROL's history are seen in the museum. The Museum of Natural History exhibits prehistoric and natural objects. The exhibition on CONTROL should actually belong in the Museum of American History.
Continuity mistake: When Agent 99 and Max are fighting the guards in Kristic's house, the hole Max and 99 used to get in disappears and reappears randomly.
Continuity mistake: In the sequence of the laser rays, Agent 99 comes out of the sewer with her shoes on. Never the less, when she begins to do her stunt to cross without touching the lasers, she has them off. Then when she has crossed, she has them on again, but we never actually see her take them off or carry them while she is crossing.
Visible crew/equipment: When you are watching the Chief fly the plane and Max wants to get out, if you look on the ground you can see that the actual freeway/highway is blocked off by a police car with detour signs or cones on the bottom right side.
Continuity mistake: When Max is entering CONTROL through all of the doors and a paper gets caught in one, the paper is moved out of frame as a whole piece of paper. When the camera moves up, the paper is now ripped in half. Even though you hear a ripping noise afterwards, enough time has not passed for the paper to be ripped and it is one continuous shot.
Continuity mistake: Prior to Max being sucked out of the plane, he holds his knife in his mouth. When he is ejected, he is still carrying it in his mouth. He screams, however, and the knife should have fallen. But Max supposedly still has the knife later in the movie. (He tells 99 to take his knife from his pocket.) It is possible he pocketed it, but unlikely, as stated in a previous mistake.
Continuity mistake: In the plane's bathroom, when Max is about to be sucked out of the plane, he has his swiss army knife in his mouth. But in the next shot, the bird's eye view of him being sucked out, his swiss army knife vanishes. It's foreseeable that in between shots Max uses his hands to pocket the knife but both the speed at which he would have to do it and the fact his hands are still clenched in the same position they were in the previous shot makes it very unlikely.
Revealing mistake: Max and Agent 23 are fighting in the car scene near the end of the film, and Max is hanging out of the car door. In some of the shots from Agent 23's POV, you can see that it is a stuntman instead of Steve Carell hanging out the car door.