Bieke's father who gets shot resisting arrest at the beginning of the film, is clearly shot on his left side of the chest. But in the shot right before he lays still, we see the gunshot wound on the other side, then it flips back again when he's down. This was a deliberate act by the director, paying tribute to John Wayne westerns where the chase between Indians and Cowboys was flipped (caused by money problems between director and producers).
When the cops are in the car with Ledda, the cops shoot out the tires. But in a later shot of the rear of the car, the tires are still intact.
When Ledda meets Bieke and her dog waterside, note how there is a boat in the background, behind Ledda. The view whips back and forth, and the boat is gone. The view whips back and forth again, and the boat is back. This was discovered one day before the DVD release, when the commentaries were being recorded, the director swore and said "That (...) boat did a Copperfield!"
Throughout the movie, the laser on Ledda's pistol is unsynchronized. In wide shots, he turns it on or off as appropriate (when hiding, he is not projecting a red light) but in all closeups the laser is on.
The laser mounted to Ledda's Beretta is not in a consistent position. Laser mounts of this era are difficult to install and it appears there are two prop guns. One has the laser mounted properly, the other has it pointed down at a 5° angle (which would make it useless for aiming). In closeups, the two are switched between in single scenes, so this is clearly a mistake, and does not indicate the character dropped the gun and misaligned the laser at some point, for example.
Near the end, when Ledda helds the doctor hostage, police tracks his actions on a monitor with USB-connection (we get to see the USB-sticker clearly several times). The movie is set in 1995. Although Compaq, DEC, Microsoft, and NEC defined the USB port in 1993, standards were approved by the group only in 1996, and the first implementation of USB did not occur until 1998.
In the scene where the two traffic cops are checking Ledda in his parked car, the second cop flies off his motorcycle before Ledda backs into him.
Ledda and Seynaeve are carrying "De Standaard" to recognize each other. While the story is set in 1995, the caption of this newspaper is the one that was introduced in 2002.
Although the movie is set in 1995, some of the mobile phones are clearly more recent models.
The movie is set in 1995, but a Coca-Cola can design that appeared after 2000 can be seen several times.
The movie is set in 1995. After stepping off the train Ledda takes the escalators down in Antwerp Central station. There weren't any escalators in there at that time.
Some of the cars carry European-style license plates (full width, with a blue European mark on the left side - most clearly seen on the Mercedes cab that Ledda rides in). These were not yet introduced in 1995, the time the movie is set.
Many of the guns used are ostensibly equipped with silencers, yet they make much more noise than such a gun would make.