OK, I get it. SPOILER ALERT!

Eddie's burning the hundred dollar bills out of the blue is foreshadowing of the ending. The problem is that if he's the devil, this isn't exactly the best way to show that. As far as I know, one of the devil's habits was never burning money. 

As it stands, the ending comes off like the song "Norwegian Wood," where out of the blue they decide to burn the house down.