It's been years since I've seen it, but when I first watched this I was completely in love with this film for reasons that I don't quite know how to put into words. It just felt like a love letter to classic Hollywood Noir and Crime Dramas. You mentioned several times that it didn't feel believable to you, but while I agree with you I also have to note that it was never the intent. The 1930s lines were just transposed onto teens and its jarring to watch, but just made for this incredibly unique experience as teens played out the tropes of classic films with deadpan seriousness.

I'd be the first to say that this film isn't for everyone and it certainly isn't without it's faults. I think that because these characters operate as the embodiment of crime archetypes of a time past, it makes it hard to care about their fates because it seems so out of reality, but for a modern entry into a dead genre of films with absolute commitment to its concept in a way that makes this film flawed but uniquely endearing to me.