A couple of Hitlers fuck ups:
-he didn’t like the StG 44, which was the first “assault rifle”. He preferred longer, heavier, high powered bolt action rifles. Thankfully his generals went behind his back and kept production of the 44 alive.
- Continuing the trend of bigger and heavier, he wanted new tanks to be that way but that was not congruent to the blitz type of army operations they were conducting. The bigger heavier vehicles bogged down in the mud and became an anchor around the mobile mech units.
- Hitler believed in bombers over fighters. Had he used the Me262 as a fighter instead of a bomber it may have changed the war. Same for the Battle of Britain if he had produced more fighters in general.
- And obviously the big mistake of going after Russia in the winter. Big fail.

Had Hitler not have been in such a hurry he may have won. He should have taken Poland, waited a few years for everyone to get used to the new normal, and then invade the next country, wait, and so on…in a decade or two he could have controlled all of Europe.
He was too stuck in the WW1 techniques and concepts of weapons.