The postcard sent from Berlin has a postage stamp with post-2001 Euro Currency on it. The postmark however says "Deutsche Bundespost" which ceased to exist in 1994. The mail business is called "Deutsche Post" since then. Also a real German postmark would look similar, but instead of "Deutsche Bundespost" would state the town (e.g. Berlin) in the top half and the ZIP-Code (e.g. 10001) in the bottom half of the outer circle.
Luther states Ethan is going to use a "fulcrum" to swing from one building to another in order to steal the Rabbit's Foot when in fact what the team uses is a pendulum. A fulcrum is a point for a lever to act upon, a pendulum swings under the influence of gravity.
When Ethan calls Musgrave to put a trace on the Rabbit's Foot, Musgrave says that he sees him on "Luang Tao Lu Road," but "Lu" in Chinese means "road." Therefore when he says "...Lu Road" it is redundant.
When Ethan is in China to retrieve the Rabbit's Foot, the four guards on top of the roof clearly communicate and visually see each other. When sliding down the roof he only shoots two of the guards, leaving the other two alone. These guards would clearly see the two fallen guards and set off the alarm right away.
When Davian is being kidnapped in the bathroom, as Hunt is coughing to kill time, the camera switches back between Hunt and the bodyguard, the tissue he is holding continually switches between his left and right hands.
SPOILER" In the final scenes of the film when Hunt and Davian are fighting, Hunt pushes Davian through the doors into the road. In the shot that the pair come rolling through the doors, we see three men standing next to the wall, looking on, however, in the next shot they are gone.
When Musgrave is speaking with Ethan in the convenience store he has a significant amount of chin and lip hair. When Ethan is watching the taped mission message from Musgrave in the next scene, he is extremely clean shaved. It could not have been taped that much earlier.
At the end of the bridge battle, Ethan leaps atop a taxi to take a shot at the helicopter. In the shot from behind, Ethan leaps directly onto the trunk lid of the red taxi with his right foot; in the immediate reverse (frontal) shot, he first pushes off the fender of the black Lincoln with his left foot and then hits the taxi with his right.
When Declan and Ethan are outside the wall in the delivery truck and have the hood up arguing, there is a male and female that are arguing with them. In one frame the female is standing with the male, then next frame the female is walking, the next frame the female is standing again with the male.
When Hunt runs at high speed down a flight of stairs to where Julia is being held captive, you can see a brief moment where the guide wire used to support him (in case of a fall down the stairs) is visible to the left of the screen. It evidently was not completely removed during editing with CGI (the line is not fully visible, so it may be that some attempt was made to remove it).
The attack to release Owen Davian is set on Virginia's Chesapeake Bay Bridge-Tunnel. After the attack, Ethan Hunt jumps into a convertible and in a very short period of time drives across the 14th Street bridge toward the Jefferson Memorial, which is about a 3 hour drive from the Bay Bridge-Tunnel (The bridge-tunnel connects the Delmarva Peninsula with southeastern Virginia).
As Ethan is just about to run through the streets of Shanghai, you can see a real map of Shanghai and the place where Ethan is. In the next scene, Ethan escapes through the rooftop and you can see a village, which in reality isn't there, because at this point of the map there are traffic routes and tourist streets. Then he runs through an old China street with old fashioned prototype Chinese, which in reality is a modern city street with normal people.
The shot of St. Peter's Basilica when Ethan is on the wall made it look like there are no trees inside the grounds of the Vatican. The actual view of St. Peter's Basilica from wall of the Vatican Gardens includes many umbrella pine trees. The shot also made St. Peter's Basilica look further away from the back wall of the Vatican than it actually is.
When Ethan is in the Mercedes convertible fleeing the scene of the bridge attack, he passes several Virigina State Police cars with red and blue roof lights headed in the opposite direction. However, Virginia law states that police vehicles in Virginia can only have blue roof lights (red lights are reserved for fire trucks, ambulances, and rescue vehicles).
A defibrillator submits an electrical charge that only affects muscles. Therefore, the charge would never make it to the brain. To try and kill the implant, a direct charge to the brain would be needed and in doing so, kill the person.
In the Vatican city, Ethan clips on what appears to be some sort of inductive wire tap over Ethernet cables to gain access to the internal security camera feed. An inductive type of tap that just goes around the entire cable would not work with Ethernet, as there are multiple pairs of conductors inside a single cable, each operating with differential signaling.
While the IMF caravan is on the Chesapeake Bay Bridge-Tunnel with Davian, all of the vehicles with Virginia tags are labeled incorrectly. Virginia license plates consist of three letters, a hyphen, and four numbers (LLL-NNNN) not three letters as shown.
When Ethan is fleeing the scene of the bridge attack in the Mercedes convertible, we see him steering with one hand and using his phone with the other, but the soundtrack indicates manual gear-changes are being performed. This can explained by the type of gear box which is either a semi-automatic or Triptonic.
In German, "IMF" would be pronounced "Ee em eff," yet the German commando in the helicopter pronounces it "Eye em eff." However, it would be perfectly normal for a German native speaker to pronounce it in English like he would for example "CIA" or "FBI".
When Ethan swings onto the roof in Shanghai, the security guards shout at each other in Mandarin. Although the Shanghaiese dialect is spoken in Shanghai, there are large numbers of "guest workers" in Shanghai, and Mandarin is widely understood. Moreover, the guards are reported to be former "Chinese Intelligence", and, as such, are likely to be drawn from all parts of the country, the majority of whom speak Mandarin.
During the infiltration of The Vatican, Ethan climbs on a thick wall beside a CCTV camera, turns it off, takes a picture of what it is seeing, prints it and hangs it before the camera before turning it back on. The Focal length of a CCTV camera is usually set to infinity, especially one that is taking a large view, meaning everything within 90 centimeters of the camera would be out of focus. The photograph was hung a few centimeters before the camera, that would make it largely out of focus.
When Ethan and Luther are using the machine to paint the Owen mask under the Vatican, the eye-holes in the mask stay white while the rest of the mask is painted. If the mask were really being painted, the head mannequin would have also be painted.
When Owen is asking Ethan where the Rabbit's Foot is in the beginning, and end, of the movie; the shots of Owen in the mirror behind Ethan are not consistent with the shots of him facing the camera. Specifically the gun position is down in the mirror shots (when Ethan is talking) and the gun is pointed at Ethan's wife while Owen is talking.
The goof items below may give away important plot points.
When Ethan's wife is performing CPR on him, she is
doing the breaths incorrectly. As a nurse, she should know to tilt his head back to clear the airway. The breathing, as she does it, does Ethan no good. In addition, CPR is designed to keep blood circulating until definitive care can be provided at a hospital. Precordial thumps (pounding the chest with a fist) can only attempt to jolt a fluttering heart back into a normal rhythm. Neither of these techniques can restart a pulseless heart, much less suddenly restore a victim to consciousness, as Ethan demonstrates.
When Ethan calls Benji Dunn from Shanghai and asks him to trace the phone where Julia is being held captive, Benji tells him the trace location is "one mile to the northeast", however the map shows the location due straight North, not Northeast as Benji stated.
In the final scenes as Ethan is running through the narrow streets of Shanghai, he is almost hit by a truck traveling at quite a speed. As he turns the corner from where the truck has just come, we can see that it is narrow and there are pedestrians in the middle of the road. Not the sort of road for trucks to be traveling at that speed.
After Ethan parachutes from the building having recovered the rabbit's foot, when he is picked up by the Land Rovers, the road condition alternates from dry to wet and back to dry again in the space of seconds.
When Ethan is having the time release capsule in his brain detonated, Julia
hides behind a wall to avoid gun fire. Her position on the wall changes to where her shoulder is over the wall and therefore able to get shot, back and forth throughout the whole sequence.
At the end of the fight between Owen and Ethan, Ethan rolls over so that Owen is on top, allowing him to be struck by the speeding truck. However, when we next see the road in which they were lying, it is a narrow side street completely blocked by stationary cars.
When the Lamborghini Gallardo explodes after Zhen and Ethan go into the sewers, you can clearly see a chain protruding from the car just as it explodes, as the crew had used one to hold down the car and control the explosion.
When Ethan is attempting to defibrillate Lindsey in the helicopter to destroy the implant, the defibrillator takes 30 seconds to charge. This time is way too long. Most defibrillators will charge to 200 joules in about 8-9 seconds and to 360 joules in about 13 seconds.
At the end of the film, when Ethan is designing an improvised defibrillator using two power cables and first testing them by putting the ends in a bowl of water and flicking the switch, that would have resulted in a short-circuit that would have blown any fuses installed along the power line thus making it impossible for him to proceed using it on himself.