The claim that "When Irena kills Osborne, she fires the gun 7 times (not 6)" is moot because the T-33 Tokarev pistol she fires holds 8 rounds in the magazine plus 1 in the chamber for a total of nine Even if the gun she picked up was that of the man who shot the dog twice, she would still have enough rounds to shoot Osborne 7 times.
When Renko shoots Iamskoy and the public baths, Iamskoy falls backward over the railing. He starts to fall straight down, which would be logical. But the aerial shot shows him landing out in the pool, in the water, several feet from the edge of the pool. He should have landed on the pool deck, not in the water.
When Arkady's car stalls on the bridge on the way back to Moscow, the wipers are still running. As Arkady repeatedly tries to re-start the car, we see the wipers still running at full speed. In real life, each time he tried to restart the car, the wipers would slow from the drain of battery power away from the wipers to the starter motor.