Why didn't the advanced German technology in the last years of World War II such as guided missiles and jet aircraft make a greater difference in the war's outcome?
The major reason for this is that they were a case of too little, too late. By the time that these weapons came online, the Allies had already invaded Europe. It was too late for the new weapons to do much good and they were not available in sufficient numbers to be decisive in any case.
Although the Me 262 jet fighter was introduced into combat just before the D-Day landings, it was only as a test concept. It was some months before significant numbers of these planes were available. Even when they did become available in larger numbers, they could not make a huge dent in the Allied forces. An example of this is a March, 1945 air raid in which Me 262s shot down 12 bombers out of over 1000 that were on the raid. Clearly, this was not going to make enough of a difference, especially since the Allied ground troops were on their way into Germany. If there had been thousands of these planes, it might have made a difference, but there were not and it did not.
Overall, then, the new German technologies were simply not ready in time to be produced in enough numbers to be decisive in the war.
I agree with the above post. In addition, the V-1 and V-2 missiles launched at London were only generally accurate, and designed to terrify and demoralize, which they did. They would have to have been used in much larger numbers and with accuracy against valuable military targets (instead of civilian, residential areas) in order to make a difference.
While the ME262 was indeed revolutionary, by the time it was developed, Germany was also facing critical shortages of fuel and even worse, qualified pilots. Hitler also interfered with the design of the jet, ordering it to be re-engineered into a bomber for retaliatory strikes on Britain instead of as a fighter that could intercept American and British bomber raids. The addition of bomb carriages and the added weight made the jet slower and less stable, therefore, it was less effective than it could have been.