Several times during the series, when we see a shot of the square in front of Antwerp City Hall, the same two cars pass by.
There are transmitters for wireless telephony visible in the offices of the BRT (the Belgian public broadcasting company), which were not yet available in the 70's.
While the story is set in the 70's, the dialog sometimes contains Dutch expressions and phrases that were not commonly used until the 90's.
Some of the cars in the series have license plates that could not have been issued yet in the 70's.