I don't think they retrieved the plane (otherwise they'd retrieve the contents as well no)? Wasn't Fox looking at a work order rather than the actual plane at the end?|
Or, maybe they did retrieve the plane, and everything inside, which explains why he's 'buried' in the grounds of Wayne Manor at the end.
Or maybe it's yet another thing we're better off not looking at too carefully.
LB, you really are a massive geek.