The production was able to shoot at some of the most iconic showdowns with the law including Lake County Jail in Crown Point, Indiana, the Little Bohemia Lodge in Manitowish Waters, Wisconsin; and the Biograph Theatre in Chicago.
"It was one of the most amazing things that Michael Mann provided us with to have that level of authenticity to be able to break through the exact doors that John Dillinger did as opposed to just shooting it on a sound stage because it's cheaper of whatever, Michael was a real stickler for that kind of thing and I will thank him forever for that.
"To fire my Thompson out of the very window that John Dillinger fired his Thompson out of at the battle of Little Bohemia you can't put a price on that," explained the actor.
"To literally be able to walk in the steps that he did, to walk the walk out of the Biograph theatre and land exactly, to the millimetre, where John Dillinger's head fell in that alley was magical and you almost feel him, and not to be moony or spooky or anything, but there were moments that I felt his presence and a certain amount of approval from the guy."
Despite all of the success that has come his way off the back of Pirates of the Caribbean Johnny admitted that he still struggles with all of the attention.
"If I could avoid the mirror when I brush my teeth in the morning then I would," he laughs. "I find security and safety in the most profound degree of ignorance, if you can just stay ignorant of almost everything that I think that you will be ok, just keep walking forward, it's ok to notice things and look at things but to judge things bog you down.
"I don't like watching myself in the movies because I don't like to be aware of the product, I like the process I enjoy that, that is not my fault (laughs) I didn't do it, I was there but I didn't do it."
Public Enemies is out now
FemaleFirst Helen Earnshaw
Tagged in Johnny Depp