In the train fight scene, after Agent 47 kicks the other blade wielding agent out of the train window. Agent 47 removes the (very bloody) blades he had already used, from the other dead agents. However after he gets down, below train level, to begin fighting once again, the blades appear clean.
With the Interpol agents coming down from the private plane, you can hear the engines powering down but when you look at the jet turbines, you don't see them moving at all.
Near the end of the film, when Interpol Inspector Michael Whittier is
sitting in the ambulance, his shirt is open, he then is shown to be buttoning it closed, but in the next shot (from far away) his shirt is still completely open. In the next shot, from up close as he stands his shirt is completely buttoned closed again.
When 47 and Nika return from the restaurant, there is no chest at the bottom of the bed, however when 47 returns from Udre's club, he throws his gloves down onto a chest at the bottom of the bed.
Nina is in the trunk of an Audi S5 but the car when they travel and talking about "male penguins" is an Audi A4 convertible.
Like many other movies portraying Interpol agents many mistakes are made concerning how Interpol works and operates. For example Interpol officers do not directly conduct inquiries in member countries and Interpol's constitution forbids its involvement in several types of crimes, such as political ones.
While pretending to be a Russian officer, Agent 47 has five stars on his shoulder strap. There are no such ranks with five stars in the Russian Army.
On the back patches of FSB uniforms, the Cyrillic letter "S" (C) is flipped left-to-right.
When the Hind gunship attacks Agent 47 in the church it has 4 UB-32 rocket launchers mounted on it. However when the camera fully shows the hind, muzzle flashes are seen from the rocket pods, even though they only fire rockets, and no rockets are fired as the ensuing explosions would have been quite noticeable.
Since the movie is filmed in Bulgaria, many road signs are in Bulgarian, not Russian.
In the scene in the hotel room in Turkey, when Nika gets up and stands on the balcony, Agent 47 is reading through papers on his target. In them Istanbul is spelt 'Istambul'. However, the name of "Istambul" is still used among many European countries.
When 47 first interrogates Nika, it appears that the tattoo on her face switches sides during the scene. This is because the camera is viewing the characters directly in some shots and views them indirectly in other shots using the large mirror present in the room.
While Agent 47 is posed as arms dealer Price, Udre Belicoff showcases several weapons. When he picks up the assault rifle, he describes it as an M203 with under-barrel grenade launcher. This is actually an M16 rifle, with M203 grenade launcher attachment. He also suggests that the rifle shoots 7.62 mm ammunition, when in fact the M16 shoots 5.56 mm. This is shown to be deliberate when 47 calls Udre out, saying "you've been wrong about most of these."
On the train when agent 47 and the three other agents are about to fight to the death, they get rid of their magazines. As they hit the floor you can see that they are full of blanks.
The train station is supposed to be in Saint Petersburg, Russia. The signs in the tunnels of the train station say it is in Moscow.
When Belicoff enters the cathedral, some Russian soldiers present at the ceremony are wearing old-fashioned helmets. They are Eastern German helmets however, not Russian ones.
While Agent 47 is fighting under the train, during one of his punches you can clearly see it's not Agent 47, but rather the Assassin who was shot earlier.
The interior shot of the Alexander Nevsky Cathedral in which Belicoff delivers a eulogy for Udre was not actually taken inside the cathedral. The hall shown is much smaller and pillars can be seen that do not appear inside the real cathedral.
The light switch in Whittier's house (which is supposed to be in London), is a broad continental Europe style switch, instead of the smaller thinner switches you find for British lights. This indicates that the scene was filmed somewhere else.
When Nika gets whipped with the antenna in the basement, the result would have left scars all over her back, yet later in the film, her back is clear and scar-free.
The opening credits is a mixture of footage created for the movie and clips from the TV show Dark Angel. Notice is in the barcodes: Hitman tattoos are above the neck and Dark Angel tattoos are on the neck itself.
In the first scene where children gets their first training there is a scene where it shows the famous tattoo is placed at the back of one of the children's neck. Later on it appears on the back of the head and much smaller.
When the female reporter starts to interview Belicoff in Saint Petersburg, what she says doesn't match her lips.
When Agent 47 and Nika are in the car while she's eating her sandwich, 47 says, "Back at the station, you interfered". The "you interfered" doesn't match up with what he's saying.
At 48:45 a wire or cable can be seen under the opposite side of the detective's car as he stands outside speaking with the Russian police.
Opening shot: entering the house, camera crew is visible in the left window just after he puts down his coat.
When the CIA stops the Interpol cars, you can see flashing blue lights of police vehicles in the background. These are from the police cars blocking the road so the scene can take place.
Interpol headquarters is located in Lyons, France and not in London.
During the movie the teletype text says, "Russian Border - Turkey." Russia not does share a border with Turkey, which borders Bulgaria and Greece (in Europe), and Armenia, Azerbaijan, Georgia, Iran, Iraq and Syria (in Asia).
The interpol agents and St. Petersburg police discuss intercepting Agent 47 at the St. Petersburg Station. However there is no St. Petersburg train station in St. Petersburg. The train station shown on the map is the Moscow Station, located in Revolution Square whereas the Leningrad (the former name for St. Petersburg) station is located in Moscow. This is because in Russia, train stations are named after the main destination they serve (there is also a Kiev station in Moscow for example). They were designed by the same architect.
When Agent 47 first leaves St. Petersburg for Moscow, the cut scene where "Moscow - Russia" is displayed on the screen is showing an image of the Kazan Cathedral, located in St. Petersburg.
On the northern hemisphere (Istanbul), when the sun is rising, it should travel from left to right and can be seen on the southern sky. It seems that the rising sun in Istanbul-shot is filmed in the southern hemisphere.
Whittier states that the passage on the cross from 47's luggage is from Psalms. It is actually a shortened version of Proverbs 3:5-6.
Agent 47 tells "Diana" that Belicoff took a bullet through the nasal cavity when Belicoff is actually shot through the forehead.