Hitlers biggest mistake was declaring war on the US. The isolationists whould never had agreed to go to war in Erurope in 41 or 42. Germany never attacked the US. That was the standard then. Had Herr Hitler waited for the V2 been developed wither multiple stages, the outcome would have been different.
Hitler had the non agreesion pact with Stalin and England was subdued.
If Hitler had not invaded the USSR, had made a separate peace with the UK in 1940, then the post WWII world would have had a three way cold war between Western democracies, Fascist Europe(Third Reich) and the USSR.