How do I change side mirror glass on a ND Miata (2017)?

Replacing a mirror glass is tricky business. The attachment is plastic and can fracture regardless of what you do -- especially if the glass is broken. This means there was impact that can deteriorate and damage other mirror components besides the glass. But you can try to change it. To do so, move the entire mirror housing back towards the body -- kind of "unfolding" the assembly. Move the glass position so that the bottom right of the driver's glass (bottom left of the passenger glass) is all the way "out" so you can slip fingers behind it in that area. Gently pull at the glass releasing the pins. The shop manual recommends using a heat gun to gently encourage the pins to come out. Good luck!