Scorsese and Pileggi collaborated on the script for five months, towards the end of 1994. Real-life characters were reshaped, such as Frank "Lefty" Rosenthal, Geri McGee, Anthony Spilotro, Spilotro's brother Michael, Spilotro's right-hand man Frank Cullotta, and mob boss Joseph Aiuppa.
Martin Scorsese's film Casino (1995) is based on the Las Vegas careers of Spilotro and Rosenthal, on whom the characters Nicholas "Nicky" Santoro (played by Joe Pesci) and Ace Rothstein (played by Robert De Niro) were based.