I happen to have the same watch in black on right now (a genuine one though).
Oke lets see:
1: The date is too small.
2. The pip on the bezel is touching the edges of the black triangle, the real one has a tiny bit of space between the edges (this is usually the best way to tell a fake Planet Ocean).
3. The x5 minute indicators on the bezel seem very short.
4. There is too little space between the printed 12, 9 and 6 and their indices. And the 12, 9 and 6 seem stretched and just plain wrong.
5. Waaaaay too much space between the date and the 3 o clock indice. (Dead giveaway this one)
6. The writing is not fine enough, seems quite smugged. (Take a look at the G on OMEGA, what happened there?)
7. It might be after market , but the real one has much nicer packaging.
8. Numerous, more subtle things
Hope he didn't pay too much for it. Fake watches are for fake people as they say....