Every studio in Hollywood turned down Ebbe Roe Smith's script. Producer Arnold Kopelson was getting to the stage of considering cable television, when Michael Douglas came across the script and pronounced it one of the best he'd ever read.
At the time of its release, Michael Douglas' father Kirk considered this to be his son's best performance.
During the Whammyburger scene, Deedee Pfeiffer as Sheila had a hard time staying in character after Bill Foster pulls out a firearm, as his lines afterward kept making her giggle and laugh. If one looks closely at her face as she's handing Rick the burger before the camera pans to Bill talking to the scared customers, you can see that she's smiling.
The man who is yelling about being "not economically viable" in front of the bank is wearing the same clothes as Foster. Even the tie pattern is the same.