Honestly, the pencil looks fine to me. I don't see any major perspective errors.
If I had one suggestion, it would be to maybe reconsider the viewing angle so his lower legs aren't foreshortening directly away from the viewer—it becomes a bit hard to read—but that would entail doing an entire new drawing.
That is not how you do an air on a surfboard. If he were doing an air on a surfboard he would be crouched and leaning forward. His face would be pointing down towards the ground (or water, whatever you want to call it).
His body would also be WAY more compressed. And his head would be looking down at where he is going to land. But the main thing is body compression. While surfing, your back is never arched like that when doing an air.
Search "Surf Backside Air" on google images for lots of references on this specific type of surfing aerial.
I just re-read my critique and I think it came off as very harsh. With that said, I was only trying to help and will next time try to be a little nicer next time. It's hard to express what you really want through text sometimes.
I just wanted to say that while the pose might be not be totally accurate to "real" surfing, you still did a good job with the character and I like the detail that you put into the weird mechanic/hydraulic things going on with this guy. Keep up the good work and I really look forward to seeing a new one of these.
Also, it's not exactly very "accurate" for a giant robot to be flying through the air and surfing, so maybe it's okay that the pose isn't as close to a more normal surfing pose. So maybe take that artistic license and screw the accuracy of the pose.