It's a good job indeed Vavavoom, but I think the reason that some parts on the aircraft look out of place is thanks to the lighting on the aircraft in relation to that of the background.
I hear you ask, "What's the remedy for this problem?"
...I have no idea.

As for the jaggy aircraft (which isn't terribly jaggy as it is), perhaps you could use a soft, weak blur tool (assuming you're using Photoshop, Paint Shop Pro or anything with a blur tool) and perhaps blur the edges slightly....

(Just I guess, I've no idea if this works

)
Other than those two problems you raised, for a first edit you've done a proper job vavavoom!
