The first killer shoots his target with a revolver 3 times. When the police confront him, he raises his revolver in order to shoot at them; in doing so, at least 4 rounds are revealed on either side, indicating that at least 4 rounds remain in the revolver which holds but 6 rounds.
When Jim watches the recorded instructions, you can see footage of the wrecked Mercedes of Alfred Herrhausen (chairman of Deutsche Bank). He was killed in it not by a "sinister force", but rather by the 3rd generation of the Red Army Fraction.