The scene where the then just 7 years old Dante first met the alien Vojajer was also the first time he actually saw that alien (Henrik Ståhl). His fear and anxiety is quite real (but by no means traumatizing - Dante could tell about it himself during Amsterdam Cinekid 2018 with a big smile).
Henrik Ståhl made the (sometimes rather funny) sounds of Vojajer himself, during the taking of the actual scene. Only a couple of sounds were edited a bit afterwards.