Faye's Mistakes
I realize the real answer to this question is that it was a plot device needed to further the movie along; however, except for that I thought Faye's decisions were pretty stupid:
Why do you want to steal money from a casino only to gamble it back? Vince, although psycho, was right. They needed to law low.
Why didn't she just wait for Jack at the hotel, pay him the rest of his cash, screw him, or "celebrate" as she had said, and then be on her merry way. If Vince had believed this, she would have nobody looking for her. If not, what is to be gained by cheating Jack and having him looking for her too? The few thousand she was supposed to pay him was small potatoes compared to the hassle.