Machine Gun Kelly sustained a hairline fracture of the sternum on set toward the end of filming, reportedly from repeat punches to the chest from an unnamed person playing a police officer. The actor claimed that when he complained to a crew member about the incident, he was told to "suck it up".
In one of the early shots of the Chicago skyline the Ryugyong Hotel was added. The Ryugyong Hotel isn't in Chicago, it's in Pyongyang, North Korea. It was started in 1987 and still sits unfinished. It's in the Guinness Book of World Records as the tallest unused building.
The coin Gabriel uses to make a pay phone call (at 40m 30s) is a "Standing Liberty" silver quarter, issued between 1916 and 1930.
Machine Gun Kelly sustained a chest injury on set of this film. Doctors requested he take a month off from touring. Despite this, he only postponed 3 shows and continued on his tour for the release of his new album; Bloom.
David J Height, who played the Master of Ceremony, during filming played various sections of the crowd in Soldier Field against one another to see which section could cheer the loudest.