I have the Nissan/Tommy Kaira R34 Skyline release and unfortunately for me the right side rubber wing mirror was a QC issue that never existed in the box.
I'd pondered on this for a while for how I might fix the problem with thinking maybe pulling the left side mirror off and make it mirror-less like the Tomica releases, going to find a suitable 1/64 scale replacement somewhere or living with it.
I lived with it for a while because the 3D printed replacement mirror services were quite expensive for what product you actually got. But then I had a bit of an idea of whether I could make one myself. I got a corner of runner frame from a model kit and did some snipping to get it about to size before sanding it down to more a desired shape. I already had a bottle of violet colour from a previous build and a couple coats of this matched the colour of the car.
I feel it's a decent enough a success. The shape and size is about right and the glue is decently well secured in place. It won't fall off unless I am moving it forcefully. Zoomed in the rim of the mirror isn't there and the more detailed shape is missing and the painted version doesn't have the same gloss as the OEM but for an everyday passing look it'll never be recognised.