Guns gore i cannoli
First off a whole New City named Thugtown exists (or rather existed) from at least 1860 (there's an Union State in the center of town and the stores sell Confederate War Memerophelia) until 1928 in the Middle of New York State, so that's probably going to lead to some butterflies, perhaps in Elections.
Then there's the scandal itself, the People will be livid when they realize the US Army lost to a bunch of Walking corpses, a handful of Mobsters and some random Enforcer with an M1911, not to mention the backlash when it's leaked that the US Government authorized the creation of Zombie Booze before then proceeding to just... LEAVE it all in Thugtown. You know, the most crime-infested city in the Country. Like, imagine what could have happened if some Villain who had goals other than ,,hurr durr respect and monies" got a hold of it back then! It was just LEFT in the Sewers, only guarded by an easily-bribable middle aged German Man.
Oh, and the main character (who is, by the In Universe Public, percived as a War Criminal becouse he's the only guy left to blame becouse everyone else in Thugtown is either a walking corpse, normal corpse or melted corpse) gets off scott free without any charges. Whatever judge gave that decision (and whatever douche gave him the job) should expect at best to be blacklisted from Politics and at worst a homemade explosive from people who lost relatives in the Massacre of '28. Butterflies again.
Also the fact that a GERMAN U-BOAT managed to get INTO THE GREAT-FUCKING-LAKES, steal a shitton of Zombie Booze (from, once again, a US GOVERNMENT FACILITY) without anyone except the Mob noticing (as opposed to, you know, the Goddamn US Army, being stationed 2 blocks away - like seriously the Lab is within earshot of the Quarantine Wall, and while granted it's the outer wall did NONE of the dozens of Soldiers stationed there suddenly notice bands of Nazis appearing out of nowhere in a supposedly ,,ghost town" where there should logicly be NOTHING LEFT ALIVE by then? That's going to hurt the Government's authority.
Also the same random mobster from before helped storm Normandy Beach and killed Hitler's right hand man (and the RHM's right hand man), he also killed every Nazi Soldat between Normandy and Bavaria so that's going to leave a mark on the Wehrmacht.
Also if the US Government salvages the Rosswell UFO then they can have Super Planes in 1944.