One surprising early development by Goddard that might have made a
difference had it been widely known was his use of ox-rich gas
generators for driving turbopumps. All those decades of US engineers
insisting it was impossible....
On the other hand, Goddard's early and soon abandoned trick of
pressurizing both oxygen and fuel tanks with gox was just as well left
in obscurity (not that learning from others' failures isn't a good idea,
but few seem to have thought to try it).