The "Hell" that Willie and Carl visit is a twisted version of New York City like out of Jacob's Ladder.
Because this may make for an interesting story, Willie and Carl would seem to have awakened back in their normal life, but things are not as they seem. Any situation they get involved in goes horribly and terrifyingly wrong, and designed to exploit their worst fears.Carl's life might be based upon his fears of being captured by the mobsters whom he was laundering money for, with him being on the run in his daily life from the mobsters tracking him down.
Willie might experience a version of New York overrun by criminals, and be unable to find a safe haven.
If they "pass their tests" and reform from their old ways, Willie and Carl can break free and be at peace, similar to the concept of Purgatory. As a nod to Jacob's Ladder, the shadows that appeared to be dragging them away were angels taking them to rehabilitation in Karmic Reform Hell.
- In light of this theory, it should be mentioned that both films have the same screenwriter, Bruce Joel Rubin.
Sam fighting back against Willie during the robbery may have doomed Sam, but it saved Molly's life
It's left ambiguous whether Willie intended to kill Sam from the get-go. He seems to imply it later on when telling Carl "I did you a favor," though that could be an after-the-fact rationalization, and it's evident that his immediate reason for killing Sam was that Sam grabbed the gun and they ended up in a death struggle. If Willie had planned to kill Sam all along, then it's quite possible he would have killed Molly if not for Sam's fighting back, to eliminate an eyewitness.