WHERETOGETPAPERPLANES.COM
The honest answer is that you cannot reliably authenticate a Paper Planes cap from a photograph, and neither can anyone else selling you a checklist for doing it.
Counterfeit-spotting guides describe the last generation of fakes.
Buy from the network. The stockist list reproduces the retailer network the brand publishes, with each shop's address and phone number, every address validated rather than copied blind.
Ask the brand. A first-party answer from someone holding the actual product beats any checklist, and it is the only route that ends in a definite answer.
The mark is embroidered rather than printed, and structured caps are built on New Era silhouettes, properties of how the product is made, not authentication markers.
Every shop, address and detail is in the full guide, and the store map covers 21 states.