When Wesley meets Sloan and company, Sloan tells him they've transferred all his assets to Wesley. When Wesley goes to his ATM to check his balance, he withdraws a large sum of money. However, when he is later viewing his account online at work, his balance displayed is exactly the same as before he withdrew the cash.
When Wesley Gibson is tied to the chair and punched in the face, a cut on the bridge on his nose disappears and re-appears in some shots.
After Fox's car drives off the bus during the first car chase, the back window shatters. Minutes later it is back, with minimal damage.
During the train crash scene, the last cars start derailing. However, in the next shot, the middle cars that are slipping off, and the back of the train is on the track.
When Wesley is in his father's apartment having everything explained to him, his hair is wet from the bath. In one shot by the window hair is sticking up on either side of his head, the next shot it is fixed, and the next shot it is sticking up again.
While undeniably cool looking, the multi-component bullets used in the sniper rifles and Cross' gun would actually have less range than a standard full metal jacket. As the bullets disassembled themselves in flight, each part that fell away would reduce stored kinetic energy imparted at the time of launch. High kinetic energy is a vital component to range, which is why a heavy 4-inch artillery shell flies further than a .50 cal bullet, which flies further than a .22.
Throughout the film, no matter how many hard objects the bullets go through, they don't slow down or stop. This film 'sets aside' this fact.
When Wesley types in his name in the search engine, www.google.com, he enters it without quotations, and gets no results. However, in order to get no results for a name, you would have to put the name in quotations, like "Wesley Gibson" - assuming there is someone by that name. If you only enter the name without quotations, like in the film, the search query will yield any results for Wesley, and any results for Gibson, (Wesley + Gibson as opposed to "Wesley Gibson") making it factually impossible for a search engine to yield zero results.
Curving a bullet as demonstrated in this film is not possible. Since no matter what direction you fire the bullet, it will always go in a straight line. This has been proven on the show Mythbusters.
At the train station, a door leads to an elevator with a sign that says "An elevator with an operator" in Czech. The accented letters in "operator" are wrong. It was most likely translated on a computer without Central European fonts, a common mistake.
Wesley hits Barry with his keyboard and the words 'FUCK YOU' fly off. A keyboard only has one letter 'U', but the final letter 'U' is one of Barry's teeth.
It's a little strange that the fraternity uses binary code, especially since the binary code that they used correlates to the ASCII chart (e.g. '01101000' translates to an 'H'). The first ASCII chart was created in 1963, and the version they use was updated in 1986. Binary code is perfectly reasonable given the explanation of how the cloth is "read". The use of ASCII specifically is strange, but any speculation on this point is moot given events that transpire later in the film.
The Fraternity would not have called themselves that 1,000 years ago. The word first appeared around 1309, as the Middle English word "fraternite." In fact, the founders would have spoken Old English, which has more in common with Old Norse than Modern English. The closest equivalent would probably be a word based on "broþor", the Old English for "brother" (as in brotherhood). The founders would not have spoken Old English. The "birthplace" of the Fraternity is revealed to be Moravia, part of the Czech Republic (where Wesley goes to confront Pekwarsky). "The Fraternity" would simply be a relatively modern English translation of the original Czech name.
As Fox is beating up Wesley, there is a punch that is divided into three shots. In the first shot, she starts the punch with her left fist, which is bare. The next shot shows her other fist, the one with the brass knuckles, coming at the camera. The third shot finishes the punch, with the bare left fist. It is more likely that the sequence was a deliberate attempt to show the speed of three separate punches.
When Sloan is showing Wesley the loom, he puts a clipboard on the fabric, which clearly demonstrates the fact that while the machinery's working, it's not really doing anything since the fabric isn't moving.
When Fox picks Wesley up after he quits his job, there is a close-up of the knife used to steal the car. The knife-blade is translucent and the entire ignition slot through it. Additionally, despite the fact that the car is moving, the speedometer is set at zero.
(At around 28 min.) The title of the network article which Wesley reads is "Gang Violence on Rooftop, 5 Dead in Mass Shooting" while text is "Eight bodies were found dead from gunshot wounds..." Also, the sub-headline refers to the "Victim's Names", which should read Victims' (plural).
When Wesley returns to his apartment to retrieve his father's gun, Barry's missing tooth is clearly blacked out.
When Fox is beating Wesley asking him "Why are you here.." Fox is seen with brass knuckles on right hand. Scene shows him being hit with brass knuckles on the right hand but in the next sequence she hits him with her left hand with the right hand with brass knuckles are in the background.
When Wesley first learns to curve the bullet and shoots at Fox, the camera shows the bullet going in slow-mo but Fox blinks at normal speed.
At the scene when Wesley is told to shoot the wings off the flies, Gunsmith holds a gun to his head. When he cocks the hammer back, there is a sound clip of a gun having the slide manipulated, not a click of a hammer.
The movie is suppose to take place in Chicago, but when Wesley drives the Mustang and Fox drives the C4 Corvette to assassinate the man in the limousine, they race through Long Island City, Queens. The Citicorp building and the New York City skyline are in the background.
After quitting his job, Wesley sees his and Fox's photo from the security camera, at the pharmacy, on the all newspapers' front pages. Once the incident at the pharmacy occurred, the police would have questioned the pharmacist who had Wesley's name for the prescription (and most likely his address also). The police would have picked him up before he went to work for questioning.
Both kill orders include a statement, starting "I Hereby Acknowedge..." It should be spelled "Acknowledge".
Wesley's first assignment, Robert Deane Darden, is described as a 48-year-old man who weighs 180 kg. (396 lbs.). It's strange that his height is given in imperial, and his weight in metric. Also, a 6'1" man weighing 180kg would be quite massive, either very muscular or very obese, whereas the man Wesley's shown to kill looks quite average. Considering other targets' weights are given in pounds, it's more likely this should have been recorded as 180 lbs - which would be quite reasonable.
Wesley tells of his girlfriend having sex with Barry on "an IKEA kitchen table I picked up for a really great price". The scene though shows them having sex on a peninsula table, attached to a kitchen counter, not a separate table.
In Wesley's opening narration, he refers to his boss Janice as anorexic, but she is very large and addicted to donuts. This is not framed as irony or sarcasm, or an outrageous claim on her part, and Wesley doesn't speak that way normally, so even if it is a joke, it's extremely confusing for the first lines of the film.
When Wesley confronts Sloan, Sloan tells the group that each of their names came up. Moments before, Wesley pointed out that Sloan was manufacturing targets, so there is no reason for Fox to believe their names had come up. There was no need for her to kill herself and the other assassins.