In the film several gray telephones are used. This is the standard Dutch national telephone company-model PTT T65, which was introduced in 1965.
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.
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.
There is a Citroën 2 CV which is a 1970 model (or later).
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.