Near the end, when Vlad grabs the gun on the desk, it's a nickel-plated semi-automatic, as he draws back his hand, he has a black semi-automatic in it, as well as in the following scenes.
At the end of movie, JCVD takes his pistol back from the little girl and puts it in his right leg holster. Seconds later, the pistol is gone.
At the end of movie, Fiona has a walkie-talkie on her belt (on the left). A few seconds later, when they meet JCVD outside, the walkie-talkie is gone.
At the shoot out at the end, the sniper pushes the bolt forward, and then does it again seconds later when he reaches the fence.
When Gaul and his son are talking in the rain, the son's umbrella keeps changing hands between shots.
Samson wakes up in a room full of meat hanging around him, and he's all sweaty. The meat would have to be stored in a refrigerator, and Samson should be cold.
When Stelu goes to church at the end, he enters a confessional. In the Eastern Orthodox Church, however, there is no anonymous confession as there is in Roman Catholicism. Confessions take place in the open at a lectern before an icon of Christ, not directly to a priest.
When the man using the Remington 700 sniper rifle chambers a cartridge, the end of the cartridge is clearly crimped. It's a blank cartridge.
The black Mercedes at the airport and the red Ferrari driven by Vlad have the same license plates C AA 147.
When Samson is looking at the newspaper left by the parents all the articles are just "Lorem ipsum dolor" filler.
About halfway through after the parents leave the hotel, JCVD & his son are arguing in the butcher shop. JCVD tells the son to leave. When he gets outside he puts his jacket on, however when JCVD goes into the back and he comes back in, he has his jacket in his arms again.
Before rising and entering the confessional, Stelu crosses himself. This is supposed to be an Eastern Orthodox church (although it's clearly Roman, as none of the film was actually shot in Moldova)), with nearly 95% of all Moldovans adhering to the Orthodox faith, but he crosses himself in the Roman style (head, chest, left shoulder, right shoulder), instead of the Orthodox style (head, chest, right shoulder, left shoulder).
The shots of Vlad watching Samson on the monitor of the security camera were filmed by a second camera which had the security camera clearly visible in the left side of the frame.
When the police come at the end of the movie, you can see a GoPro camera attached to one of the guns that army is using.
The plot in the movie is supposed to take place in Moldova, mainly the capital Kishinev. Yet in most scenes shot outside the cars display Romanian license plates. Example: The cars parked on the street across the American Embassy clearly show a "B" which implies the vehicles are registered in Bucharest, Romania.
Police cars that are shown approximately 25 minutes into the movie are clearly from the US. They appear to be LAPD.