Near the beginning of the film, when Castor Troy turns round and sees his brother Pollox Troy being pinned down by cops, the camera zooms in on Pollox's face as he shouts "CAS!". However judging by the lip movement and expression of Pollox, it's obvious that the word was dubbed over the video.
During the hangar shootout one of Archer's federal agents is killed with a shotgun blast (we get a good look at his face), yet a few moments later you notice the same agent is standing, alive and well.
When Archer (As Troy) was being strapped into the electrical chair, they took off his magnetic boots (exposing his bare feet). During the prison riot Archer was wearing some kind of black shoes and it wasn't until he jumped off the oil rig when his feet were bare again.
In the beginning of the movie, Sean Archer is sitting on the merry-go-round with his son, Michael, and the bullet goes through Sean's chest and into Michael's head, shown by the amount of blood that seems to be dripping from Michael's forehead. Later in the movie, though, a summary of Michael's death shows that the bullet was through his chest, not his head. It's about 21 minutes into the movie.
Just before Dubov gets shot by Walton, we see Burke Hicks running up to Walton to try to stop him. A few minutes later when Dubov falls down and Walton tries to shoot Castor, Burke Hicks runs up to Walton again.
In the last scene where Archer (as Castor) is fighting Castor (as Archer), Archer screams in pain when Castor hits him, but it's Castor's voice. In the previous scene, the microchip in his larynx was dislodged, so he spoke as Archer again.
When Castor Troy (C. Troy) and Sean Archer (S. Archer) are having their faces switched in the laboratory, the monitor for Castor Troy shows his name as "T. Castor". When in fact it would read either "Troy. Castor" or "Troy. C". Hospitals/ Institutions always record patient details as: Surname. First Name / Initial.
On the plane at the beginning of the movie, Castor (still Cage) passes his drink to his left hand when the stewardess sits on his lap, however, a second later he's putting a cigarette to his lips with his left hand, and the drink is back in his right.
Just after Castor Troy activates the bomb in the LA Covention Centre, he walks behind a choir girl, says something to her, then grabs her hair, in the first shot we see of them she has a bit of hair hanging down next to her ear, but in the next shot, Castor has all of her hair in his hand pulling it back from her face.
Just before Sean (as Castor Troy) goes to Erewhon Prison, his friend Tito says there are 6 days until the 18th, when the bomb is supposed to go off. Just before that, though, there's a shot of the bomb that says there are 216 hours until it explodes. Tito could have meant six days after Sean got out of Erewhon, the bomb would go off, but Sean is supposed to be in Erewhon two days, which means the bomb would go off in a maximum of eight days. 216 hours, though, is nine days, not eight. That clarifies the meaning of what Tito said, but the time frame is still incorrect.
When Dubov falls over the hand rail after getting shot, Archer (as Castor) holds onto the barrel of the gun and his hand is slipping. His hand clearly changes position on the barrel between different camera angles.
After they recieve Archer in the office with applause for catching Castor, he checks the computer for his son's file. It states he was murdered on Sept. 9th, 1991. However, later in the movie, when they go to the cemetery on Michael's birthday, the grave states Sept. 24th, 1991.
When Castor Troy is captured at the beginning of the movie, he is clearly in possession of his famous twin 1911 gold-plated gun, yet later, when Archer goes to Dietrich's apartment, Dietrich gives him the same guns.
On the runway, when Castor arrives in his car, he is wearing three gold rings - one on his right hand (ring finger) and two on his left (pinky and middle finger.) In the plane, a clear shot of one of his hands shows that he is wearing a ring on his pinky only. Whichever hand this is, right or left, it is inconsistent with the previous scene.
When Archer (as Troy) is fighting with Dubov in prison, he hits him several times with the metal tray. Before Archer hits Dubov, he is hitting him like a left-handed baseball player, but after impact the camera switches angles and he continues through the hit as a right-handed baseball player.
In the boat chase scene, we see Troy (as Archer) take a swing at Archer's face (as Troy) with the anchor, miss, and leave a hole in the boat. In the next shot, the part of the boat where there is supposed to be a hole, is perfectly smooth.
When Sean Archer is holding the bottle from the CIA, he holds it at the base of the bottle in the quick shot while he is walking around his secretary but in the closeup shot of him putting the bottle down, he is holding it at the top.
When Archer and Castor are lying in the stretchers after Castor has been killed, there is a lot of blood on the collar of each of their shirts. in the next scene the blood pattern changes so there is almost no blood, but in the scene immediately after, the blood returns. This is evidence that the shirts were changed during the filming.
When Archer/Troy is escaping from Erewhon he starts off barefoot, and is seen with shoes on in various shots. One shot he is barefoot, the next he has shoes. This is evident in several different shots.
During Archer's escape from Erewhon, the computer screen that flashes Castor Troy and Dubov's names also displays Pollux Troy's name in the same list. However, Pollux Troy had already been released and is no longer an inmate at Erewhon.
Immediately after the motorcycle cop pulls up during the Convention Center evacuation montage there is a wide shot of the frenzied street; in the background a camera crane with camera and operators is visible as it tracks upward.
When the swat team begins shooting into Dietrich Hassler's apartment, Archer grabs Sasha and her son, and jump behind the bed. Dietrich is then seen sitting in a chair, as Dietrich stands and begins to walk, a camera can clearly be seen rising behind and to the left of him.
The Geneva Convention regulates the treatment of victims and prisoners of war, not criminal prisoners of society. The guard saying that the Convention does not apply in the prison means nothing, it doesn't apply in any civilian prison.
Near the end of the raid on Dietrich's place, Loomis busts in armed with a Colt M4, with an underslung M203 Grenade Launcher. He fires the launcher twice in rapid succession. The M203 is a one-shot launcher and requires reloading between shots. There is no indication that Loomis bothered to reload at all.
In the funeral scene, the flag draping the casket is lying in an incorrect orientation. It is conventional for the union of a United States flag to be at the head and on the left side of the body, covering the heart.
At the end of the movie when Archer adopts Adam and brings him to his home, Eve looks very surprised. It is very likely that California state law would require written consent from both parents for adoption.
During the raid on Dietrich's apartment, Archer (as Castor) grabs a FBI SWAT member and says "Buzz" as he remembers him, however at that exact point, Dietrich is seen behind Archer's right shoulder. Archer makes out that he "killed" the SWAT member, but Dietrich saw Archer compromise his cover and then fire one round into the floor.
When Castor sets the bomb it is set for 236 hours (just about 10 days) after the initial surgery, there is a shot of the bomb indicating it was about 216 hours. There is no way that the surgery and subsequent healing process, in addition to the chase, capture, interrogation, etc. that took place in such a short interim.
When Castor as Archer reads Eve's journal the latest date reads the 17th which would put it the day before the bomb at the convention center was to explode. But as he reads it, the text states the Archer had come home after catching Castor and told her that he had to go back on assignment. The events described would actually have happened on the 7th, according to the movie's time line.
After Pollux falls through the skylight, Troy (as Archer) is visibly upset. When Loomis enters the room, you can clearly see the "bullet hole" covered up on his forehead; it is also visible when he says "It's just Pollux Troy" and Troy shoots him in the head, exactly where the makeup-covered mark is. You can see it explode with the impact of the shot.
The helicopter broke off the Aileron instead of the Horizontal Stabilizer (Pitch Control). The jet still can take off with broken aileron but not advise to do so since it is dangerous in the air. The aileron control the turning but the experienced pilot can control the yaw with left and right engine power output.