I think my 50 Centimes coin is an error [solved]

It is coin alignment (flip it vertically) and has a head on the obverse. When I flip it vertically, the head faces northwest!

Welcome to numista.

Make a cropped image of your coin in front of a mirror, please

You can see from the year lines of available coins that there are both „coin“ and „medal“ alignment available for various years of this coin. Coin alignment is common but medal alignment does exist.

When I flip it vertically, the head faces northwest!

Not south or north so not coin or medal alignment. So 45° off  But as already suggested, a picture is needed.

A picture is taken

Now that I checked mine it is the same as well as the 20 centimes 1954.

As a Belgian I can attest that this is a regular occurrence with these coins. Apart from true medal alignment (which are known, and 1953 is not one of those years) there is no real interest in slight variations like this. Just a curiosity.