The 2007/08 Arsenal Away shirt was made by Nike. The main flaw that appears in the fake-replicas is the absence of the "NikeFIT" logo at the bottom right.
On the contrary, the fake shirts do have the writing "DRI-FIT" on the back right. The original shirt ends with a blue stripe; the fakes ones end with a red line instead.
The golden writings (Fly Emirates, Nameset) of the original shirts are yellow in the fake ones. Overall, the original shirt's fabric looks much brighter than the fake ones'.