Ah, I see. I must admit I assumed everything was saved with the object. Thanks!
One more further question: what’s the best practise then for when releasing a game; do I just store the texture jpg’s inside the game’s jar, or is there a better way, like using BinaryExporter on all the textures?
You can store an image in a j3o but thats not optimal for the mentioned reasons. It has to if the image is packed in the blend files because there is no image file available. As the documentation says you should unpack your images from blend files or even better use the blend file and textures right from the assets folder.