Anachronism not found in the "goofs" section
In film time, J.Edgar is attending a showing of the Cagney movie G-Men about 10 minutes earlier than the arrest of Hauptmann takes place. In reality, G-Men premiered in April 1935 while Hauptmann had already been apprehended in September 1934. Seems like an unbelievably big oversight... unless there was some deliberate shuffling of chronological order going on within the earlier timeline.
"facts are stupid things" Ronald Reagan