So the only thing I see that is suspicious is the minute sub-dial for the chronograph, but I don't have a reduced, so could be wrong about how they work. On the Professional, the 'minute' is a 'jump minute', meaning the minute indicates '0' until the second hand is ~2 seconds from 0, and then 'jumps' or 'clicks' quickly to '1'. I see right there that the minute hand is half way between 0 and 1.
Otherwise, I don't see anything suspicious (but again, I'm no expert). Chronographs are particularly difficult to fake (in that one of the hands is seemingly always 'doing the wrong thing' on the fakes), usually the 12 hr subdial being replaced with an additional 'hour' hand.
To get this authenticated, you'd have to go to some local Omega expert shop, no normal 'goldsmith' could take a look and make a reasoned opinion. You'd want the case back removed so the movement could be authenticated: I am not aware of any fake reduced Speedmaster (or professional!) movement that would pass a knowing eye looking inside the case back.