Factual errors: In the film, Baby Face Nelson was killed in a shootout with agents in Wisconsin after the robbery of the Security National Bank at Sioux Falls, South Dakota. In fact, he was killed due to injury's suffered in a shootout with FBI agents in "The Battle Of Barrington" in a northwest suburb of Chicago on November 27, 1934.
Factual errors: In the opening sequence, Walter Dietrich is shown being killed in the Michigan City breakout on September 26, 1933. Dietrich was actually captured on January 6, 1934, and returned to the Indiana State Prison at Michigan City. Massive bloodshed is shown in the Michigan City sequence, when in fact only one man, a clerk, was wounded. Further, Dillinger was killed before Dietrich's death.
Factual errors: In the scene where John Dillinger is in the police station with officers listening to a baseball game on the radio, the game is the Chicago Cubs vs. NY Yankees. Since those teams only played in the World Series in late Sep to early Oct 1932 and Dillinger was in prison from 1924 until being paroled in May 1933, there is no way it could be the Cubs vs. Yankees on the radio. There was no interleague play back then except for the World Series and they never broadcast spring training games on the radio way back then.
Factual errors: Pretty Boy Floyd, killed in the beginning of the movie by Purvis, was actually killed on October 22, 1934, exactly 3 months after Dillinger died.
Factual errors: In the scene where Dillinger escapes from the Indiana prison the soldiers that are guarding the prison are wearing the shoulder insignia (Gold Cross on Black Background) of the 33d Infantry Division, Illinois Army National Guard.
If you want more I will list them. When I was in high school I did a report on John Dillinger, thats how I new about most of the error's.