In Chapter Two you can see the actor Chris Zegers in a living room. There is a table in the middle with an Elvis Presley record underneath. That record was released in 1968 (1977 in the Netherlands). However, the movie is set in 1963.
The jeep used by the soldier to leave the camp has a yellow license plate which became common in the seventies/eighties. But is for real a army plate because of the characters KP. The big military vehicles do have gray plates but no army plates.
One of the military vehicles has a yellow license plate, which arrived in Holland in 1978. Another military vehicle has a blue license plate that starts with DE. Those are especially for classic cars and were introduced in 1988, although the movie plays in 1963.
The weather forecaster on the TV reports that a "weather alarm" has been issued, but the concept of weather alarm was first introduced in the Netherlands in 2001 (http://nl.wikipedia.org/wiki/Weeralarm) and the movie is set in 1963.