The bank heist sequence was done entirely in one take, with no one outside the principal actors and people inside the bank aware that a movie was being filmed. When John Dall as Bart Tare says, "I hope we find a parking space," he really meant it, as there was no guarantee that there would be one. In addition, at the end of the sequence someone in the background screams that there's been a bank robbery - this was actually a bystander who saw the filming and assumed the worst.
Although Bart and Laurie are loosely based on Bonnie and Clyde, the scene where they hold up the factory appears to have been inspired by a holdup at the Nashville, Arkansas, Coca-Cola Factory in 1938 by two men, Floyd Hamilton and Huron "Terrible Ted" Walters. Hamilton was a former associate of Bonnie and Clyde's.
Spoiler: When Bart is reading about the deaths at the meat packing plant, he says that the security guard's name was William Bechtel. It is unclear as to whether or not this can be taken as a nod to comedian William Bechtel.