The kidnapper named "Rem Hubrechts" was actually named Willem Holleeder.
There actually was a fifth kidnapper, not shown in the movie, called Martin "Remmetje" Erkamps.
They used his nickname and gave it to Hubrechts because they couldn't use the name Willem Holleeder because he is still around and threatened with a law suit if they used his name in the movie.
When Alfred Heineken (Rutger Hauer) is liberated in the Nissen hut, one of the Policemen is armed with an AK 47. This weapon was never used by Dutch Police or armed forces.
The soundtrack of De Heineken Ontvoering, featuring the score of this movie by Tom Holkenborg (Junky XL), plus an extra song titled "Me Again" as performed by Franklin Brown, was released on Otober 15, 2011.
The weapon mentioned above is not an AK-47 but an M2 carbine. They had a curved magazine like the AK... The insignia on the berets are not correct. These did not yet exist in 1983.
Heineken's driver Ab Doderer was the brother of a well known Dutch actor and comedian Joop Doderer.