Bradley Cooper's father was ill with terminal cancer during the filming of this movie, and Cooper was accordingly relieved that the movie was shot in his hometown of Philadelphia and he could check on his father every day.
Carl Van Loon's (Robert De Niro's) limo is a Maybach 62, manufactured by Daimler AG. Daimler created the ultra-premium Maybach marque after their failed attempt to purchase Rolls-Royce and Bentley. Maybach production began in 2002, and ceased in 2013.
In the film, Ned Eisenberg is portrayed as a cutthroat lawyer. This would be his second portrayal as such a character, the first being on Law & Order: Special Victims Unit (1999), where he played defense attorney Roger Kressler.
Eddie Morra (Bradley Cooper) refers to the fact that his father sold supplies and equipment to dental surgeries, the same job Charlie's father had in the novel "Flowers for Algernon", which was a possible inspiration for this film.
The trivia items below may give away important plot points.
Near the end of the movie, we see Eddie (Bradley Cooper) has written a novel called "Illuminating the Dark Fields", a resemblance to the novel "The Dark Fields" by Alan Glynn, on which this movie was based.
Eddie learned how to quadruple his money daily. He decides to borrow one hundred thousand dollars from a loan shark to speed up the gains. He would have made one hundred thousand dollars on his own in just over twenty-four hours, if he kept quadrupling his money daily.