Agreed they had some wonder weapons late in the war. For instance jet powered fighters could have turned things around, had Hitler not been fixated on bombers and leveling English cities.

They also had a submarine propulsion system that used self-oxidizing fuel (like what's used now on many rockets) meaning they could stay underwater for longer periods of time, and weren't restricted to lead-acid battery propulsion and so could go much faster underwater than before. I don't think there was anything beyond a single prototype, but it could have restarted the Atlantic War.