He was illegally in possession of a stolen car and a bunch of hypodermic syringes, add in the cap pistol, the disguise and the demand note all being discovered at or about the scheduled opening time of the store and the fact that most cash registers are electronically-controlled and likely empty at opening time and I think they could prosecute him on capital-stupidity charges.
I missed the stolen car... the rest should not be crimes other than what you've pointed out, "of stupidity."
Possession of a stolen car -- that's a possible crime. Did he know it was stolen? Hypodermic needles are legal, afaik. Diabetics and cenacer patients, etc, make use of them daily.