1. What would have happened had France and Britian moved into the Rhineland when the Nazi's occupied it ?
2. How might things have been different had the Czech's not been pressured into handing the Sudetenland over to Hitler, thus taking away a large part of their border defenses ?
3. How might the war against Russia have been different had Hitler not ordered Field Marshall von Paulus to stay in Stalingrad way past the point where such an attack could have succeeded ?
This could go on for a while.

I can already think of three more I'd probably ask about this topic.