I'm a buzzkill, but re: Frank's head (moderate spoilers)
So Frank never takes the head off. I get the sense of magical realism and/or hipster absurdity where this could have taken place among his bandmates and associates while they were in Europe when they found Jon, but did Frank not fly and go through Customs/other airport security between Europe and the US (and vice versa) Even if he flew separate from the band, he surely would not have taken the head off just for the flight and agents?
If anyone can postulate some sort of explanation, I'd love that. If not, I totally get that I'm looking too closely for answers where the questions needn't be posed.