DID THEY REALLY? CONTAINS SOME SPOILERS. SORT OF.
Watching Osombie the other day reminded me that I'd had this on the unwatched pile for several months. It seems to be regarded as a minor cult title in the so-bad-it's-good golden turkey genre, though it doesn't look to have ever gone through the BBFC so has probably never had an official British release (it's available in various American boxsets of obscure and public domain material). It was originally shot as The Madmen Of Mandoras in 1963, but then extended for TV screenings several years later with the splicing in of about 20 indifferently shot minutes of twaddle and backstory and an attention-grabbing new title (along with an inappropriate electric piano score that's at odds with the stock music of the main film). It's difficult to say for sure, but the film is probably better in its shorter version simply because most of the new footage is at the start and so it takes a lot longer to get going.
The flash of genius at the centre of They Saved Hitler's Brain is that they didn't just save his brain, they saved his entire head and kept it alive in a glass jar in the backwoods of the tiny South American banana republic of Mandoras: eighteen years later the Nazis are set to rise again with the aid of a lethal nerve agent knows as G-Gas (it can kill an elephant in twelve seconds). Only wise old professor Coleman knows the antidote for a G-Gas attack but mysteriously the Nazis decide not to just kill him; they also abduct his halfwitted daughter but then apparently let her go, and wait around until his other daughter, her husband, various rebels, the Mandoran president and the chief of police get their act together and defeat the overwhelming might of the Fourth Reich with a 20 mph car chase and three hand grenades.
Early on, our hero and his wife dispose of a freshly murdered man by simply propping the corpse up in a public telephone box and legging it. In the middle of one chase, the film switches from day to night simply because the makers only had access to footage of a car crash at night (it's from Thunder Road, apparently). But there really isn't much point in detailing the idiocies of the movie in either incarnation: for one thing the Internet's nowhere near big enough and for another it's too easy to just descend into Mystery Science Theatre snark: it's a cheap, silly Z-movie that's somehow survived the decades since this sort of nonsense was deemed fit to screen in cinemas. Technically it's mostly better made than, say, Plan 9 From Outer Space or Robot Monster, but since when was that any kind of claim to superiority?